[7.x] Remove legacy applications and legacy mode (#75987)

[pgayvallet]

Backports the following commits to 7.x:

• Remove legacy applications and legacy mode (Remove legacy applications and legacy mode #75987)

[kibanamachine]

💛 Build succeeded, but was flaky

• continuous-integration/kibana-ci/pull-request
• Commit: d7a85d4
• Flaky suites:
  • xpack-kibana-ciGroup6

---

Test Failures

X-Pack Security API Integration Tests.x-pack/test/security_api_integration/tests/session_idle/cleanup·ts.security APIs - Session Idle Session Idle cleanup "before each" hook for "should properly clean up session expired because of idle timeout"

Link to Jenkins

Standard Out

Failed Tests Reporter:
  - Test has failed 1 times on tracked branches: https://github.com/elastic/kibana/issues/76239

[00:00:00]       │
[00:00:00]         └-: security APIs - Session Idle
[00:00:00]           └-> "before all" hook
[00:00:00]           └-: Session Idle cleanup
[00:00:00]             └-> "before all" hook
[00:00:00]             └-> should properly clean up session expired because of idle timeout
[00:00:00]               └-> "before each" hook: global before each
[00:00:00]               └-> "before each" hook
[00:00:00]                 │ info [o.e.c.m.MetadataMappingService] [kibana-ci-immutable-debian-tests-xxl-1599128900163467916] [.kibana_1/sFd4DhEqQ3W5wJH21XLBmg] update_mapping [_doc]
[00:00:00]                 │ info [o.e.c.m.MetadataCreateIndexService] [kibana-ci-immutable-debian-tests-xxl-1599128900163467916] [.kibana_security_session_1] creating index, cause [api], templates [.kibana_security_session_index_template_1], shards [1]/[0]
[00:00:00]                 │ info [o.e.c.m.MetadataIndexTemplateService] [kibana-ci-immutable-debian-tests-xxl-1599128900163467916] adding template [.kibana-event-log-7.10.0-template] for index patterns [.kibana-event-log-7.10.0-*]
[00:00:00]                 │ info [r.suppressed] [kibana-ci-immutable-debian-tests-xxl-1599128900163467916] path: /.kibana_security_session*/_delete_by_query, params: {q=*, refresh=true, index=.kibana_security_session*}
[00:00:00]                 │      org.elasticsearch.action.search.SearchPhaseExecutionException: all shards failed
[00:00:00]                 │      	at org.elasticsearch.action.search.AbstractSearchAsyncAction.onPhaseFailure(AbstractSearchAsyncAction.java:538) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.action.search.AbstractSearchAsyncAction.executeNextPhase(AbstractSearchAsyncAction.java:309) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.action.search.AbstractSearchAsyncAction.onPhaseDone(AbstractSearchAsyncAction.java:569) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.action.search.AbstractSearchAsyncAction.onShardFailure(AbstractSearchAsyncAction.java:387) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.action.search.AbstractSearchAsyncAction.access$100(AbstractSearchAsyncAction.java:68) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.action.search.AbstractSearchAsyncAction$1.onFailure(AbstractSearchAsyncAction.java:245) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.action.search.SearchExecutionStatsCollector.onFailure(SearchExecutionStatsCollector.java:73) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.action.ActionListenerResponseHandler.handleException(ActionListenerResponseHandler.java:59) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.action.search.SearchTransportService$ConnectionCountingHandler.handleException(SearchTransportService.java:403) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.transport.TransportService$6.handleException(TransportService.java:638) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.transport.TransportService$ContextRestoreResponseHandler.handleException(TransportService.java:1179) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.transport.TransportService$DirectResponseChannel.processException(TransportService.java:1288) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.transport.TransportService$DirectResponseChannel.sendResponse(TransportService.java:1262) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.transport.TaskTransportChannel.sendResponse(TaskTransportChannel.java:61) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.transport.TransportChannel.sendErrorResponse(TransportChannel.java:56) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.action.support.ChannelActionListener.onFailure(ChannelActionListener.java:51) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.search.SearchService.lambda$runAsync$0(SearchService.java:414) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingRunnable.run(ThreadContext.java:651) [elasticsearch-7.10.0-SNAPSHOT.jar:7.10.0-SNAPSHOT]
[00:00:00]                 │      	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) [?:?]
[00:00:00]                 │      	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) [?:?]
[00:00:00]                 │      	at java.lang.Thread.run(Thread.java:832) [?:?]
[00:00:00]                 └- ✖ fail: security APIs - Session Idle Session Idle cleanup "before each" hook for "should properly clean up session expired because of idle timeout"
[00:00:00]                 │      Error: [search_phase_execution_exception] all shards failed
[00:00:00]                 │       at respond (/dev/shm/workspace/kibana/node_modules/elasticsearch/src/lib/transport.js:349:15)
[00:00:00]                 │       at checkRespForFailure (/dev/shm/workspace/kibana/node_modules/elasticsearch/src/lib/transport.js:306:7)
[00:00:00]                 │       at HttpConnector.<anonymous> (/dev/shm/workspace/kibana/node_modules/elasticsearch/src/lib/connectors/http.js:173:7)
[00:00:00]                 │       at IncomingMessage.wrapper (/dev/shm/workspace/kibana/node_modules/lodash/lodash.js:4949:19)
[00:00:00]                 │       at endReadableNT (_stream_readable.js:1145:12)
[00:00:00]                 │       at process._tickCallback (internal/process/next_tick.js:63:19)
[00:00:00]                 │ 
[00:00:00]                 │ 

Stack Trace

{ Error: [search_phase_execution_exception] all shards failed
    at respond (/dev/shm/workspace/kibana/node_modules/elasticsearch/src/lib/transport.js:349:15)
    at checkRespForFailure (/dev/shm/workspace/kibana/node_modules/elasticsearch/src/lib/transport.js:306:7)
    at HttpConnector.<anonymous> (/dev/shm/workspace/kibana/node_modules/elasticsearch/src/lib/connectors/http.js:173:7)
    at IncomingMessage.wrapper (/dev/shm/workspace/kibana/node_modules/lodash/lodash.js:4949:19)
    at endReadableNT (_stream_readable.js:1145:12)
    at process._tickCallback (internal/process/next_tick.js:63:19)
  status: 503,
  displayName: 'ServiceUnavailable',
  message: '[search_phase_execution_exception] all shards failed',
  path: '/.kibana_security_session*/_delete_by_query',
  query: { q: '*', refresh: true },
  body:
   { error:
      { root_cause: [],
        type: 'search_phase_execution_exception',
        reason: 'all shards failed',
        phase: 'query',
        grouped: true,
        failed_shards: [] },
     status: 503 },
  statusCode: 503,
  response:
   '{"error":{"root_cause":[],"type":"search_phase_execution_exception","reason":"all shards failed","phase":"query","grouped":true,"failed_shards":[]},"status":503}',
  toString: [Function],
  toJSON: [Function] }

---

Build metrics

@kbn/optimizer bundle module count

id	value	diff	baseline
core	559	-2	561

async chunks size

id	value	diff	baseline
maps	3.3MB	-31.0B	3.3MB
timelion	598.5KB	-17.0B	598.5KB
total		-48.0B

page load bundle size

id	value	diff	baseline
core	1.2MB	-10.8KB	1.2MB
dashboard	708.2KB	-16.0B	708.2KB
discover	229.3KB	-16.0B	229.3KB
globalSearchProviders	9.9KB	-22.0B	9.9KB
kibanaLegacy	247.3KB	-402.0B	247.7KB
savedObjects	236.7KB	-340.0B	237.0KB
visualizations	406.9KB	-16.0B	406.9KB
total		-11.6KB

oss distributable file count

id	value	diff	baseline
total	28989	-1	28990

distributable file count

id	value	diff	baseline
total	47176	-1	47177

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream