[improve][broker] Add retry for start service unit state channel (ExtensibleLoadManagerImpl only)

[Demogorgon314]

trafficstars

Motivation

When the service unit state channel fails to start, it will throw an exception, and after the PR https://github.com/apache/pulsar/pull/22977 , it will fail forever, because the pulsar broker cannot catch the exception, and it won't have any retry mechanism

Modifications

Add retry for start service unit state channel

Documentation

• [ ] doc
• [ ] doc-required
• [x] doc-not-needed
• [ ] doc-complete

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 14.28571% with 24 lines in your changes missing coverage. Please review.

Project coverage is 74.48%. Comparing base (bbc6224) to head (5989cce). Report is 548 commits behind head on master.

Files	Patch %	Lines
...dbalance/extensions/ExtensibleLoadManagerImpl.java	14.28%	23 Missing and 1 partial :warning:

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #23230      +/-   ##
============================================
+ Coverage     73.57%   74.48%   +0.91%     
- Complexity    32624    33684    +1060     
============================================
  Files          1877     1922      +45     
  Lines        139502   144784    +5282     
  Branches      15299    15837     +538     
============================================
+ Hits         102638   107842    +5204     
+ Misses        28908    28673     -235     
- Partials       7956     8269     +313     

Flag	Coverage Δ
inttests	27.61% <14.28%> (+3.03%)	:arrow_up:
systests	24.70% <0.00%> (+0.38%)	:arrow_up:
unittests	73.84% <14.28%> (+0.99%)	:arrow_up:

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

Files	Coverage Δ
...dbalance/extensions/ExtensibleLoadManagerImpl.java	77.13% <14.28%> (-2.95%)	:arrow_down:

... and 534 files with indirect coverage changes

[BewareMyPower]

Let me merge it since there is no new response from @lhotari. Please open a new PR if you found something wrong.