Fix the issue of high CPU load caused by continuously creating new ConsistentHashSelector instances under high concurrency.

[DustinQiao]

What is the purpose of the change?

Fix the issue of high CPU load caused by continuously creating new ConsistentHashSelector instances under high concurrency.

issue link: #15496

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

All modified and coverable lines are covered by tests ✅

Project coverage is 60.88%. Comparing base (a0b6e47) to head (c8236f6).
Report is 1 commits behind head on 3.3.

Additional details and impacted files

@@             Coverage Diff              @@
##                3.3   #15497      +/-   ##
============================================
- Coverage     60.91%   60.88%   -0.03%     
- Complexity       12    11461   +11449     
============================================
  Files          1898     1907       +9     
  Lines         86477    86661     +184     
  Branches      12965    12987      +22     
============================================
+ Hits          52678    52765      +87     
- Misses        28358    28442      +84     
- Partials       5441     5454      +13     

Flag	Coverage Δ
integration-tests-java17	33.01% <0.00%> (-0.03%)	⬇️
integration-tests-java8	33.06% <0.00%> (-0.08%)	⬇️
samples-tests-java17	31.38% <0.00%> (-0.07%)	⬇️
samples-tests-java8	29.29% <0.00%> (+0.04%)	⬆️
unit-tests	58.81% <100.00%> (-0.02%)	⬇️

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