fix triple graceful shutdown

[EarthChen]

What is the purpose of the change?

Checklist

• Make sure there is a GitHub_issue field for the change.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit-test to verify your logic correction. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Make sure gitHub actions can pass. Why the workflow is failing and how to fix it?

[codecov-commenter]

Codecov Report

❌ Patch coverage is 26.92308% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.74%. Comparing base (49ecb04) to head (4cb3dcc).
⚠️ Report is 22 commits behind head on 3.3.

Files with missing lines	Patch %	Lines
...bo/remoting/exchange/PortUnificationExchanger.java	45.45%	5 Missing and 1 partial ⚠️
...g/transport/netty4/NettyPortUnificationServer.java	0.00%	6 Missing ⚠️
...ng/transport/netty/NettyPortUnificationServer.java	0.00%	4 Missing ⚠️
...l/tri/transport/TripleServerConnectionHandler.java	33.33%	1 Missing and 1 partial ⚠️
...ava/org/apache/dubbo/remoting/api/GoAwayEvent.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                3.3   #15920      +/-   ##
============================================
- Coverage     60.74%   60.74%   -0.01%     
- Complexity    11704    11705       +1     
============================================
  Files          1938     1939       +1     
  Lines         88694    88700       +6     
  Branches      13387    13388       +1     
============================================
+ Hits          53880    53883       +3     
- Misses        29285    29286       +1     
- Partials       5529     5531       +2     

Flag	Coverage Δ
integration-tests-java21	32.45% <26.92%> (+0.06%)	⬆️
integration-tests-java8	32.43% <26.92%> (+0.03%)	⬆️
samples-tests-java21	32.05% <15.38%> (-0.05%)	⬇️
samples-tests-java8	29.70% <15.38%> (+0.09%)	⬆️
unit-tests-java11	59.03% <26.92%> (-0.02%)	⬇️
unit-tests-java17	58.51% <26.92%> (-0.03%)	⬇️
unit-tests-java21	58.52% <26.92%> (-0.03%)	⬇️
unit-tests-java25	58.48% <26.92%> (+<0.01%)	⬆️
unit-tests-java8	59.03% <26.92%> (-0.01%)	⬇️

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