Fix RpcInvocation attribute cloning

[6mmLIU]

What is the purpose of the change?

Fix the issue where RpcInvocation's copy constructor shares the same attributes map with the source invocation.
This causes cloned invocations to be affected by later mutations to the original attributes, which is unexpected for a deep clone.
The change clones the attributes map and adds a unit test to verify the behavior.

Fixes #16069

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 63.63636% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.75%. Comparing base (f27d0d7) to head (d237757).

Files with missing lines	Patch %	Lines
.../java/org/apache/dubbo/common/utils/LRU2Cache.java	63.63%	5 Missing and 3 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                3.3   #16070      +/-   ##
============================================
- Coverage     60.75%   60.75%   -0.01%     
- Complexity    11751    11753       +2     
============================================
  Files          1951     1951              
  Lines         88992    89008      +16     
  Branches      13418    13422       +4     
============================================
+ Hits          54070    54077       +7     
- Misses        29362    29369       +7     
- Partials       5560     5562       +2     

Flag	Coverage Δ
integration-tests-java21	32.16% <59.09%> (-0.03%)	⬇️
integration-tests-java8	32.30% <59.09%> (-0.01%)	⬇️
samples-tests-java21	32.21% <63.63%> (+0.02%)	⬆️
samples-tests-java8	29.76% <59.09%> (-0.11%)	⬇️
unit-tests-java11	59.02% <63.63%> (+<0.01%)	⬆️
unit-tests-java17	58.51% <63.63%> (+0.02%)	⬆️
unit-tests-java21	58.50% <63.63%> (-0.01%)	⬇️
unit-tests-java25	58.47% <63.63%> (+<0.01%)	⬆️
unit-tests-java8	59.02% <63.63%> (-0.01%)	⬇️

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[zrlw]

1. Are you sure LRU2Cache has something to do with RpcInvocation's copy constructor?
2. As for me, RpcInvocation's copy constructor shares the same attributes map with the source invocation by design.