[Logs UI] Use fields api in log stream

[afgomez]

Summary

Closes #76506

Use the fields API in the logs stream to fetch the column values and log item details. This enables using special fields like aliases and runtime fields in the log stream.

Perf

I have used drill to measure the performance impact. All benchmarks are run locally in development mode, with a ES snapshot, with the following setup

drill.yml

base: 'http://USER:PASSWORD@localhost:5601'
concurrency: 5
iterations: 1000

plan:
  - name: 'URL prefix'
    assign:
      key: prefix
      value: '' # development proxy prefix

  - name: '/entries'
    request:
      url: /{{ prefix }}/api/log_entries/entries
      method: POST
      body: '{"sourceId":"default","startTimestamp":1599474418756,"endTimestamp":1599560820261,"query":null,"after":{"time":1599560802000,"tiebreaker":2477}}'
      headers:
        User-Agent: "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:81.0) Gecko/20100101 Firefox/81.0"
        Accept: '*/*'
        Accept-Language: "en-GB,en;q=0.8,es-ES;q=0.5,es;q=0.3"
        Accept-Encoding: "gzip, deflate"
        Content-Type: "application/json"
        kbn-version: "8.0.0"

  - name: '/item'
    request:
      url: /{{ prefix }}/api/log_entries/item
      method: POST
      body: '{"sourceId":"default","id":"{{ item }}"}'
      headers:
        User-Agent: "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:81.0) Gecko/20100101 Firefox/81.0"
        Accept: '*/*'
        Accept-Language: "en-GB,en;q=0.8,es-ES;q=0.5,es;q=0.3"
        Accept-Encoding: "gzip, deflate"
        Content-Type: "application/json"
        kbn-version: "8.0.0"
    with_items:
      - "enM_bXQBgxm20xYC_gj9"
      - "R3M_bXQBgxm20xYCJAgm"
      - "3XM9bXQBgxm20xYCxAf7"
      - "3HM9bXQBgxm20xYCxAf7"
      - "_nM-bXQBgxm20xYCRQdo"

• /entries before

Time taken for tests      14.0 seconds
Total requests            1000
Successful requests       1000
Failed requests           0
Requests per second       71.55 [#/sec]
Median time per request   69ms
Average time per request  70ms
Sample standard deviation 7ms

• /entries after

Time taken for tests      13.7 seconds
Total requests            1000
Successful requests       1000
Failed requests           0
Requests per second       73.01 [#/sec]
Median time per request   68ms
Average time per request  68ms
Sample standard deviation 7ms

• /item before

Time taken for tests      34.5 seconds
Total requests            5000
Successful requests       5000
Failed requests           0
Requests per second       144.74 [#/sec]
Median time per request   29ms
Average time per request  34ms
Sample standard deviation 18ms

• /item after

Time taken for tests      32.7 seconds
Total requests            5000
Successful requests       5000
Failed requests           0
Requests per second       153.07 [#/sec]
Median time per request   29ms
Average time per request  33ms
Sample standard deviation 17ms

Checklist

Delete any items that are not applicable to this PR.

• Unit or functional tests were updated or added to match the most common scenarios

[elasticmachine]

Pinging @elastic/logs-metrics-ui (Team:logs-metrics-ui)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 528c82a

Build metrics

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@elasticmachine merge upstream

[Kerry350]

LGTM 🎉

Thanks for the performance benchmarks, nice to see a little boost.