[ISSUE #10197] Add traffic size distribution per requestCode in RemotingCodeDistributionHandler

[RongtongJin]

Which Issue(s) This PR Fixes

• Fixes [Enhancement] Add traffic size distribution per requestCode in RemotingCodeDistributionHandler #10197

Brief Description

Add per-requestCode traffic size (bytes) distribution to RemotingCodeDistributionHandler, in addition to the existing request count distribution.

Key changes:

• Replace 4 ConcurrentHashMaps with 2 using a composite TrafficStats class (LongAdder count + LongAdder trafficSize)
• calcCommandSize() default path: fixed overhead (29 bytes) + body length — O(1), no iteration on hot path
• enableDetailedTrafficSize in NettyServerConfig: when enabled, also counts remark + extFields byte lengths. Togglable at runtime via updateBrokerConfig
• NettyRemotingServer.printRemotingCodeDistribution() now logs inbound/outbound traffic snapshots

How Did You Test This Change?

• Added RemotingCodeDistributionHandlerTest with 10 unit test cases covering: count, traffic with/without body, detailed mode on/off, snapshot reset, multiple requestCodes, non-RemotingCommand passthrough, concurrent correctness, and runtime toggle
• Added RemotingCodeDistributionBenchmark (JMH) comparing detail-off vs detail-on across 1/4/8 threads. recordInbound() is called directly (package-private) to isolate recording overhead from Netty pipeline cost

[codecov-commenter]

Codecov Report

❌ Patch coverage is 96.42857% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 48.86%. Comparing base (e100743) to head (dd2bb4b).
⚠️ Report is 2 commits behind head on develop.

Files with missing lines	Patch %	Lines
...ing/protocol/remoting/RemotingProtocolHandler.java	0.00%	1 Missing ⚠️
...emoting/netty/RemotingCodeDistributionHandler.java	96.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop   #10198      +/-   ##
=============================================
- Coverage      48.93%   48.86%   -0.08%     
+ Complexity     13384    13369      -15     
=============================================
  Files           1373     1373              
  Lines          99924    99940      +16     
  Branches       12908    12913       +5     
=============================================
- Hits           48898    48835      -63     
- Misses         45098    45161      +63     
- Partials        5928     5944      +16     

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[guyinyou]

lgtm

[fuyou001]

LGTM