Add regression test for NettyChannel cleanup on repeated disconnects

[SURYAS1306]

What is the purpose of the change?

This PR adds a regression test to validate the NettyChannel lifecycle cleanup behavior.
The test ensures that channels can be safely removed and re-created across repeated
add/remove cycles, preventing channel map leaks observed in issue #16054.

What is changed?

• Added a unit test in NettyChannelTest to cover repeated channel add/remove scenarios.

Checklist

• The issue has been investigated and is already fixed in the codebase
• Added a regression test to prevent future regressions
• All tests pass locally

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.75%. Comparing base (f27d0d7) to head (5f7c374).

Additional details and impacted files

@@             Coverage Diff              @@
##                3.3   #16068      +/-   ##
============================================
- Coverage     60.75%   60.75%   -0.01%     
+ Complexity    11751    11750       -1     
============================================
  Files          1951     1951              
  Lines         88992    88992              
  Branches      13418    13418              
============================================
- Hits          54070    54063       -7     
- Misses        29362    29367       +5     
- Partials       5560     5562       +2     

Flag	Coverage Δ
integration-tests-java21	32.17% <ø> (-0.02%)	⬇️
integration-tests-java8	32.30% <ø> (+<0.01%)	⬆️
samples-tests-java21	32.18% <ø> (-0.02%)	⬇️
samples-tests-java8	29.87% <ø> (+<0.01%)	⬆️
unit-tests-java11	59.01% <ø> (-0.01%)	⬇️
unit-tests-java17	58.49% <ø> (+<0.01%)	⬆️
unit-tests-java21	58.49% <ø> (-0.02%)	⬇️
unit-tests-java25	58.48% <ø> (+<0.01%)	⬆️
unit-tests-java8	59.01% <ø> (-0.02%)	⬇️

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[zrlw]

why add such codes?

[SURYAS1306]

Thanks for pointing this out.

That change is not related to the NettyChannel regression test and should not be part of this PR. It was brought in unintentionally from earlier local branch history.

I’ll clean up the PR to keep it focused only on the NettyChannel regression test.

[SURYAS1306]

Thanks for the review @zrlw ,

I’ve cleaned up the PR history to remove the unrelated commits.
This PR now contains only a single commit that adds the NettyChannel regression test
covering repeated add/remove scenarios (no functional changes).

All checks pass locally and in CI.