[improve][broker] Add logging to leader election

[lhotari]

Motivation

It's useful to have more visibility to leader election. Adding logging to different conditions will be useful especially when debugging issues.

Modifications

• add broker ids to the leader election logging in PulsarService
  • this is useful in multi-broker tests
• add low level logging to LeaderElectionImpl

Documentation

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

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 85.71429% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 72.72%. Comparing base (bbc6224) to head (6a80538).
Report is 218 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #22645      +/-   ##
============================================
- Coverage     73.57%   72.72%   -0.85%     
+ Complexity    32624    32344     -280     
============================================
  Files          1877     1887      +10     
  Lines        139502   141014    +1512     
  Branches      15299    15478     +179     
============================================
- Hits         102638   102554      -84     
- Misses        28908    30603    +1695     
+ Partials       7956     7857      -99     

Flag	Coverage Δ
inttests	27.10% <50.00%> (+2.51%)	⬆️
systests	24.63% <42.85%> (+0.30%)	⬆️
unittests	71.49% <85.71%> (-1.35%)	⬇️

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	82.36% <66.66%> (-0.01%)	⬇️
...metadata/coordination/impl/LeaderElectionImpl.java	76.21% <90.90%> (-2.63%)	⬇️

... and 337 files with indirect coverage changes