[ISSUE #9992] Fix remoting server netty server codec thread reuse problem

[ymwneu]

Which Issue(s) This PR Fixes

Fixes #9992

Brief Description

When creating NettyRemotingServer, if the serverNettyWorkerGroupEnable parameter is set to false, Netty’s codec and handshake will use Netty’s built-in thread pool. However, some other parts of this class still use the business-layer–created defaultEventExecutorGroup. In this case, Netty’s codec may behave abnormally.

How Did You Test This Change?

[lizhimins]

Nice work

[codecov-commenter]

Codecov Report

❌ Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 48.74%. Comparing base (7fc5452) to head (24e5bbd).

Files with missing lines	Patch %	Lines
...e/rocketmq/remoting/netty/NettyRemotingServer.java	88.88%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #9993      +/-   ##
=============================================
- Coverage      48.80%   48.74%   -0.06%     
+ Complexity     12775    12757      -18     
=============================================
  Files           1327     1327              
  Lines          96441    96441              
  Branches       12440    12438       -2     
=============================================
- Hits           47065    47013      -52     
- Misses         43631    43671      +40     
- Partials        5745     5757      +12     

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