[improve][broker] don't do load shedding when metadata service not available

[congbobo184]

Motivation

don't do load shedding when metadata service not available.

if unload bundle when metadata service not available, these topics which in this bundle can't recover the current ledger and send read again

Modifications

1. check metadata service state when do load shedding task
2. do not interrupt the task are doing in the same time

Verifying this change

• Make sure that the change passes the CI checks.

(Please pick either of the following options)

This change is a trivial rework / code cleanup without any test coverage.

(or)

This change is already covered by existing tests, such as (please describe tests).

(or)

This change added tests and can be verified as follows:

(example:)

• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository:

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.48%. Comparing base (bbc6224) to head (2bc63f2).
Report is 460 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #23040      +/-   ##
============================================
- Coverage     73.57%   73.48%   -0.10%     
- Complexity    32624    33196     +572     
============================================
  Files          1877     1915      +38     
  Lines        139502   143948    +4446     
  Branches      15299    15727     +428     
============================================
+ Hits         102638   105773    +3135     
- Misses        28908    30071    +1163     
- Partials       7956     8104     +148     

Flag	Coverage Δ
inttests	27.85% <85.71%> (+3.27%)	⬆️
systests	24.78% <57.14%> (+0.45%)	⬆️
unittests	72.52% <100.00%> (-0.32%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...n/java/org/apache/pulsar/broker/PulsarService.java	83.47% <100.00%> (+1.10%)	⬆️
...he/pulsar/broker/loadbalance/LoadSheddingTask.java	76.92% <100.00%> (+4.19%)	⬆️

... and 497 files with indirect coverage changes