[fix][proxy] Fix memory leaks in ParserProxyHandler

[lhotari]

Fixes #25138

Motivation

There's a memory leak in Pulsar Proxy's ParserProxyHandler which is used for development / debugging purposes.

Modifications

• Replace the usages of static final maps that leaked instances
• Handle closing of producers and consumers.
• Clear topic stats when proxy log level is set to a value < 2
• Deduplicate topic name instances in the per-connection producerIdToTopicName/consumerIdToTopicName maps

Documentation

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

[codecov-commenter]

Codecov Report

❌ Patch coverage is 87.03704% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.41%. Comparing base (1708933) to head (4a5c3d6).
⚠️ Report is 7 commits behind head on master.

Files with missing lines	Patch %	Lines
...apache/pulsar/proxy/server/ParserProxyHandler.java	85.71%	5 Missing and 2 partials ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             master   #25142       +/-   ##
=============================================
+ Coverage     36.42%   74.41%   +37.98%     
- Complexity    13094    33605    +20511     
=============================================
  Files          1706     1902      +196     
  Lines        140911   150075     +9164     
  Branches      16351    17470     +1119     
=============================================
+ Hits          51323   111674    +60351     
+ Misses        82571    29474    -53097     
- Partials       7017     8927     +1910     

Flag	Coverage Δ
inttests	26.30% <0.00%> (-0.14%)	⬇️
systests	23.00% <0.00%> (?)
unittests	73.94% <87.03%> (+39.63%)	⬆️

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

Files with missing lines	Coverage Δ
...apache/pulsar/proxy/server/DirectProxyHandler.java	72.88% <100.00%> (+20.11%)	⬆️
...a/org/apache/pulsar/proxy/server/ProxyService.java	80.81% <100.00%> (+30.25%)	⬆️
...apache/pulsar/proxy/server/ParserProxyHandler.java	83.96% <85.71%> (+83.96%)	⬆️

... and 1505 files with indirect coverage changes

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