fix(instanceset): round rolling update replicas up

[leon-ape]

Summary

• calculate percentage-based rollingUpdate.replicas by rounding up in both the legacy Pod and Instance API update paths
• preserve the conservative rollingUpdate.maxUnavailable behavior: round percentages down and clamp the result to at least 1
• correct the API documentation and regenerate the affected CRD and API reference artifacts
• keep the regression coverage in the conventional reconciler_update_test.go files
• synchronize the branch with the latest main

For three instances with both fields set to 34%, the resolved quotas are replicas: 2 and maxUnavailable: 1. This lets the requested rollout window make progress without increasing the established unavailability budget.

Tests

• scripts/codex-go-test.sh ./pkg/controller/instanceset -run TestAPIs -ginkgo.focus="update reconciler test" -count=1
• scripts/codex-go-test.sh ./pkg/controller/instanceset2 -run TestParseReplicasNMaxUnavailable -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 64.94%. Comparing base (3ebf861) to head (cd6a568).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10676      +/-   ##
==========================================
+ Coverage   64.85%   64.94%   +0.09%     
==========================================
  Files         506      506              
  Lines       63316    63335      +19     
==========================================
+ Hits        41062    41132      +70     
+ Misses      18611    18571      -40     
+ Partials     3643     3632      -11     

Flag	Coverage Δ
unittests	64.94% <100.00%> (+0.09%)	⬆️

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[leon-ape]

/approve