fix: PVCs being garbage-collected despite retention policy

[leon-ape]

cherry picked from commit 7a1c7f6

[apecloud-bot]

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[leon-ape]

/nopick

[codecov]

Codecov Report

❌ Patch coverage is 10.00000% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 53.83%. Comparing base (2df3178) to head (ac2df50).
⚠️ Report is 2 commits behind head on release-1.0.

Files with missing lines	Patch %	Lines
pkg/controller/instanceset/reconciler_deletion.go	10.00%	18 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           release-1.0   #10043      +/-   ##
===============================================
+ Coverage        53.73%   53.83%   +0.09%     
===============================================
  Files              493      493              
  Lines            54822    54838      +16     
===============================================
+ Hits             29460    29523      +63     
+ Misses           22420    22374      -46     
+ Partials          2942     2941       -1     

Flag	Coverage Δ
unittests	53.83% <10.00%> (+0.09%)	⬆️

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