Respect metadata env refs in PUB resize checks

[Jayant-kernel]

Ⅰ. Describe what this PR does

Teach PodUnavailableBudget in-place resize checks to reject a resize as harmless when Pod labels or annotations changed and a container reads the changed key through downward API env.

This fills the existing TODO in CanResizeInplace and keeps PUB from treating this kind of update as safe when the metadata value can affect the running container environment.

Ⅱ. Does this pull request fix one issue?

Related to #1192

Ⅲ. Describe how to verify it

Added TestCanResizeInplace cases for:

• referenced label changed
• unrelated label changed
• referenced annotation changed

Not run locally because Go tooling is not installed in this environment.

Ⅳ. Special notes for reviews

NONE

[kruise-bot]

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[Copilot]

Pull request overview

This PR updates PodUnavailableBudget’s in-place resize safety check to treat label/annotation changes as potentially disruptive when those metadata keys are referenced by containers via downward-API env vars, aligning PUB’s “harmless resize” decision with metadata-driven env behavior. It also adds unit tests covering referenced vs unrelated metadata changes during a resize.

Changes:

• Add metadata-change detection in CanResizeInplace for downward-API env references to labels/annotations.
• Reuse pkg/util/containermeta helpers to detect env references to metadata.labels['key'] / metadata.annotations['key'].
• Extend TestCanResizeInplace with cases for referenced label/annotation changes and an unrelated-label change.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
pkg/control/pubcontrol/pub_control.go	Adds a metadata/env reference check to PUB in-place resize gating logic.
pkg/control/pubcontrol/pub_control_test.go	Adds unit test cases validating the new metadata/env reference behavior.

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[codecov]

Codecov Report

❌ Patch coverage is 84.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 49.93%. Comparing base (c9ada9a) to head (c0f1f22).

Files with missing lines	Patch %	Lines
pkg/control/pubcontrol/pub_control.go	84.00%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2501      +/-   ##
==========================================
+ Coverage   49.91%   49.93%   +0.02%     
==========================================
  Files         325      325              
  Lines       28437    28462      +25     
==========================================
+ Hits        14194    14213      +19     
- Misses      12588    12591       +3     
- Partials     1655     1658       +3     

Flag	Coverage Δ
unittests	49.93% <84.00%> (+0.02%)	⬆️

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