[improve] [broker] Part 2 of PIP-370: add metrics "pulsar_replication_disconnected_count"

[poorbarcode]

Motivation

see also PIP-370: configurable remote topic creation in geo-replication

Modifications

• Add metrics defined in the PIP

Documentation

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

Matching PR in forked repository

PR in forked repository: x

[codecov-commenter]

Codecov Report

❌ Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 74.52%. Comparing base (bbc6224) to head (2f9de9d).
⚠️ Report is 1299 commits behind head on master.

Files with missing lines	Patch %	Lines
...ker/stats/prometheus/NamespaceStatsAggregator.java	80.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #23213      +/-   ##
============================================
+ Coverage     73.57%   74.52%   +0.94%     
- Complexity    32624    34224    +1600     
============================================
  Files          1877     1922      +45     
  Lines        139502   144754    +5252     
  Branches      15299    15832     +533     
============================================
+ Hits         102638   107874    +5236     
+ Misses        28908    28622     -286     
- Partials       7956     8258     +302     

Flag	Coverage Δ
inttests	27.70% <0.00%> (+3.11%)	⬆️
systests	24.68% <0.00%> (+0.36%)	⬆️
unittests	73.88% <85.71%> (+1.04%)	⬆️

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

Files with missing lines	Coverage Δ
...ker/stats/prometheus/AggregatedNamespaceStats.java	100.00% <100.00%> (ø)
...r/stats/prometheus/AggregatedReplicationStats.java	100.00% <ø> (ø)
...che/pulsar/broker/stats/prometheus/TopicStats.java	98.41% <100.00%> (+4.21%)	⬆️
...ker/stats/prometheus/NamespaceStatsAggregator.java	94.21% <80.00%> (+3.80%)	⬆️

... and 539 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.