Merge pull request #60683 from nilebox/pod-template-validation-fix

Automatic merge from submit-queue (batch tested with PRs 60683, 60386). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Fix PodTemplate validation

**What this PR does / why we need it**:
This is a bugfix for pod template validation, which can be reproduced by deleting with "foreground deletion" mode (`DeleteOptions.PropagationPolicy = metav1.DeletePropagationForeground`).
Because of this bug GC will never delete a pod template with `foregroundDeletion` finalizer.

**Special notes for your reviewer**:
The issue was originally found and confirmed in the PR #59851, where switching to foreground deletion in `kubectl` broke a unit test revealing this bug.
Extracted for easier backporting to releases as suggested in https://github.com/kubernetes/kubernetes/pull/59851#discussion_r171576397

/cc @liggitt @caesarxuchao 
/sig api-machinery

```release-note
NONE
```

pkg/apis/core/validation/validation.go

@@ -3503,7 +3503,7 @@ func ValidatePodTemplate(pod *core.PodTemplate) field.ErrorList {
 // ValidatePodTemplateUpdate tests to see if the update is legal for an end user to make. newPod is updated with fields
 // that cannot be changed.
 func ValidatePodTemplateUpdate(newPod, oldPod *core.PodTemplate) field.ErrorList {
-	allErrs := ValidateObjectMetaUpdate(&oldPod.ObjectMeta, &newPod.ObjectMeta, field.NewPath("metadata"))
+	allErrs := ValidateObjectMetaUpdate(&newPod.ObjectMeta, &oldPod.ObjectMeta, field.NewPath("metadata"))
 	allErrs = append(allErrs, ValidatePodTemplateSpec(&newPod.Template, field.NewPath("template"))...)
 	return allErrs
 }