tests(lb): clean flex ips + add delete waiter

[yfodil]

Community Note

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Relates OR Closes #0000

Release note for CHANGELOG:

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 88.88889% with 2 lines in your changes missing coverage. Please review.

Project coverage is 70.71%. Comparing base (5bf53e0) to head (ddb8270).
Report is 427 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/namespaces/lb/v1/custom_lb.go	88.88%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4409      +/-   ##
==========================================
- Coverage   75.45%   70.71%   -4.74%     
==========================================
  Files         202      297      +95     
  Lines       44323    65894   +21571     
==========================================
+ Hits        33444    46598   +13154     
- Misses       9653    17654    +8001     
- Partials     1226     1642     +416     

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