bugfix: the issue of possible infinite loop when cleaning up expired metadata info

[funky-eyes]

What is the purpose of the change?

fix #15087

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

Attention: Patch coverage is 94.44444% with 1 line in your changes missing coverage. Please review.

Project coverage is 60.76%. Comparing base (628dcbf) to head (0c7f59b).

Files with missing lines	Patch %	Lines
...ubbo/registry/client/AbstractServiceDiscovery.java	94.44%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                3.3   #15086      +/-   ##
============================================
- Coverage     60.76%   60.76%   -0.01%     
- Complexity    10863    10865       +2     
============================================
  Files          1882     1882              
  Lines         86007    86007              
  Branches      12886    12887       +1     
============================================
- Hits          52263    52262       -1     
- Misses        28301    28304       +3     
+ Partials       5443     5441       -2     

Flag	Coverage Δ
integration-tests	32.99% <16.66%> (+0.01%)	⬆️
samples-tests	29.09% <16.66%> (-0.13%)	⬇️
unit-tests	58.93% <94.44%> (ø)

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