fix(instanceset): round rolling update percentages up

[leon-ape]

Summary

• calculate rollingUpdate.replicas percentages with round-up semantics
• calculate rollingUpdate.maxUnavailable percentages with round-up semantics
• add regression coverage for a 34% value across three instances

The API documentation specifies that percentage values are rounded up; the previous implementation passed roundUp=false in both the legacy Pod and Instance API paths.

Tests

• go test -mod=mod ./pkg/controller/instanceset2 -run TestParseReplicasNMaxUnavailableRoundsPercentUp -count=1
• go test -mod=mod ./pkg/controller/instanceset -run TestParseReplicasNMaxUnavailableRoundsPercentUp -count=1

Fixes #10641

[apecloud-bot]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 63.92%. Comparing base (12611aa) to head (42e0fd4).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10676      +/-   ##
==========================================
- Coverage   63.97%   63.92%   -0.05%     
==========================================
  Files         520      520              
  Lines       62887    62887              
==========================================
- Hits        40229    40199      -30     
- Misses      19071    19092      +21     
- Partials     3587     3596       +9     

Flag	Coverage Δ
unittests	63.92% <100.00%> (-0.05%)	⬇️

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