chore: patch metadata-only pod updates

[weicao]

Problem

After a successful reconfigure, the remaining Pod diff can be metadata-only, for example a config-hash annotation update. The release-1.0 InstanceSet path already skips switchover for safe metadata-only in-place updates, but ObjectTree.Update still plans a full update. That can leave the Pod metadata stale when the update path should use a merge patch.

Changes

• Add an ObjectTree patch option and plan a PATCH vertex when requested.
• Use PATCH for safe metadata-only in-place Pod updates in the release-1.0 InstanceSet reconciler.
• Add focused coverage for PATCH planning and the InstanceSet metadata-only call site.

Backport boundary

This is a manual release-1.0 backport of #10401. release-1.0 does not have the separate pkg/controller/instance reconciler path from main, so this PR intentionally changes only the release-1.0 InstanceSet path plus shared kubebuilderx planning code.

Validation

• go generate -x ./pkg/testutil/k8s/mocks/...
• go test ./pkg/controller/kubebuilderx ./pkg/controller/instanceset -count=1
• git diff --check origin/release-1.0..HEAD

Backport for #10369 via #10401.

[apecloud-bot]

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[codecov]

Codecov Report

❌ Patch coverage is 89.47368% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 53.94%. Comparing base (fb30697) to head (4d3a848).
⚠️ Report is 1 commits behind head on release-1.0.

Files with missing lines	Patch %	Lines
pkg/controller/instanceset/reconciler_update.go	71.42%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           release-1.0   #10403      +/-   ##
===============================================
+ Coverage        53.86%   53.94%   +0.08%     
===============================================
  Files              494      494              
  Lines            55688    55698      +10     
===============================================
+ Hits             29994    30049      +55     
+ Misses           22706    22654      -52     
- Partials          2988     2995       +7     

Flag	Coverage Δ
unittests	53.94% <89.47%> (+0.08%)	⬆️

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[leon-ape]

/recheck-cla

[github-actions]

✅ CLA recheck triggered. The status should update shortly.