[improve] Improve logic for enabling Netty leak detection

[lhotari]

Motivation

Currently it's tricky and confusing to enable the Netty leak detector for Pulsar broker and Pulsar clients.

The current logic expects that pulsar.allocator.leak_detection is set. The standard property for Netty is io.netty.leakDetection.level (legacy property io.netty.leakDetectionLevel).

One additional challenge in setting the pulsar.allocator.leak_detection property is that the value is case sensitive. It must be set to Disabled, Simple, Advanced or Paranoid instead of disabled, simple, advanced or paranoid.

Modifications

• Allow setting the Netty leak detector for Pulsar brokers and Pulsar clients by setting any one of the following system properties:
  • io.netty.leakDetectionLevel (legacy Netty property)
  • io.netty.leakDetection.level (standard Netty property)
  • pulsar.allocator.leak_detection (Pulsar's property)
• When multiple properties are set, use the setting with the highest leak detection level.
• Use case insensitive parsing of the setting since it's currently case sensitive.

Documentation

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

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.37%. Comparing base (bbc6224) to head (6d7cc65).
Report is 743 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #23613      +/-   ##
============================================
+ Coverage     73.57%   74.37%   +0.80%     
- Complexity    32624    34987    +2363     
============================================
  Files          1877     1944      +67     
  Lines        139502   147134    +7632     
  Branches      15299    16224     +925     
============================================
+ Hits         102638   109438    +6800     
- Misses        28908    29253     +345     
- Partials       7956     8443     +487     

Flag	Coverage Δ
inttests	27.52% <100.00%> (+2.93%)	⬆️
systests	24.36% <100.00%> (+0.03%)	⬆️
unittests	73.76% <100.00%> (+0.91%)	⬆️

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

Files with missing lines	Coverage Δ
...ulsar/common/allocator/PulsarByteBufAllocator.java	68.29% <100.00%> (+5.43%)	⬆️

... and 660 files with indirect coverage changes

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