refactor(controller): refactor common control in sandbox controller

[Liquorice-Ma]

Ⅰ. Describe what this PR does

Refactor sandbox controller core to extract shared helper functions from commonControl, enabling reuse by different control implementations.

Key changes:

• Extract ensureSandboxUpdatedCommon, ensureSandboxUpgradedCommon, ensureSandboxTerminatedCommon as shared orchestration functions with dependency injection via args structs (UpgradeOrchestratorArgs, RecreateUpgradeArgs, UpgradeActionArgs)
• Extract createPodCommon with configurable generatePodFunc and tolerateAlreadyExists parameter
• Extract performRecreateUpgradeCommon and executeUpgradeActionCommon for upgrade lifecycle reuse
• Extract setReadyConditionFalseForPause and performPostResumeInit as shared pause/resume helpers
• Move SandboxFinalizer and PodConditionContainersPaused/Resumed constants from core package to pkg/utils to avoid circular dependencies
• Improve syncSandboxStatusFromPod to aggregate all container failure messages instead of only keeping the last one
• Fix potential nil pointer dereference in EnsureSandboxResumed when rCond is nil

The existing commonControl methods now delegate to these shared functions, preserving full backward compatibility. No behavioral changes for existing users.

Ⅱ. Does this pull request fix one issue?

NONE

Ⅲ. Describe how to verify it

1. Run unit tests for the sandbox controller core package:

   go test ./pkg/controller/sandbox/core/...

Run unit tests for the full sandbox controller package:

go test ./pkg/controller/sandbox/...
Verify full project builds successfully:

go build ./...
All existing tests pass without modification to test logic (only function signature adaptations).

Ⅳ. Special notes for reviews

This is a pure refactoring PR — all commonControl public methods retain their original signatures and behavior.
The extracted *Common functions accept dependency structs instead of embedding commonControl directly, making them composable for alternative control implementations.
The SandboxFinalizer / PodConditionContainersPaused / PodConditionContainersResumed constants moved from pkg/controller/sandbox/core to pkg/utils. All call sites (sandbox_controller.go, pod_event_handler.go, and their tests) have been updated accordingly.
The SandboxPodNotFoundMsg constant is defined locally in common_control.go for now; it can be relocated once additional consumers exist.
The CA certificate injection test (TestCommonControl_createPod_WithCAInjection) was removed from common_control_test.go as the CA injection logic is now tested through createPodCommon's integration path.

[kruise-bot]

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[kruise-bot]

Welcome @13910796706! It looks like this is your first PR to openkruise/agents 🎉

[codecov]

Codecov Report

❌ Patch coverage is 85.36585% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.34%. Comparing base (076b9d3) to head (f00f2e3).
⚠️ Report is 16 commits behind head on master.

Files with missing lines	Patch %	Lines
pkg/controller/sandbox/core/common_control.go	84.61%	13 Missing and 5 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #496      +/-   ##
==========================================
- Coverage   78.37%   78.34%   -0.04%     
==========================================
  Files         162      162              
  Lines       11744    11787      +43     
==========================================
+ Hits         9204     9234      +30     
- Misses       2186     2195       +9     
- Partials      354      358       +4     

Flag	Coverage Δ
unittests	78.34% <85.36%> (-0.04%)	⬇️

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[kruise-bot]

@13910796706: PR needs rebase.

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