Merge pull request #65908 from juanvallejo/jvallejo/switch-delete-strategy-background

Automatic merge from submit-queue (batch tested with PRs 64695, 65982, 65908). 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>.

switch delete strategy to background deletion

**Release note**:
```release-note
"kubectl delete" no longer waits for dependent objects to be deleted when removing parent resources
```

### Before 1.11.0

- Resources that had client-side reapers in older versions of the client had all of their dependents deleted first. The parent resource itself was deleted *last*. This allowed the command to be re-entrant and was largely an artifact of it **having** to be done that way by a client-side reaper.

### After 1.11.0 (with this PR)

- Resources that previously had client-side reapers are no longer deleted last (after their dependents). They are now instead deleted first. The garbage-collector server-side then deletes any dependents.
- This means that the `delete` command can return, and the parent object can be deleted while child objects still exist.
  - This is okay because the child resources are eventually deleted by the garbage collector server-side. 

cc @liggitt @soltysh

pkg/kubectl/cmd/delete.go

@@ -240,7 +240,7 @@ func (o *DeleteOptions) DeleteResult(r *resource.Result) error {
 		if o.GracePeriod >= 0 {
 			options = metav1.NewDeleteOptions(int64(o.GracePeriod))
 		}
-		policy := metav1.DeletePropagationForeground
+		policy := metav1.DeletePropagationBackground
 		if !o.Cascade {
 			policy = metav1.DeletePropagationOrphan
 		}

pkg/kubectl/cmd/delete_test.go

@@ -137,9 +137,9 @@ func TestOrphanDependentsInDeleteObject(t *testing.T) {
 		}),
 	}
 
-	// DeleteOptions.PropagationPolicy should be Foreground, when cascade is true (default).
-	foregroundPolicy := metav1.DeletePropagationForeground
-	policy = &foregroundPolicy
+	// DeleteOptions.PropagationPolicy should be Background, when cascade is true (default).
+	backgroundPolicy := metav1.DeletePropagationBackground
+	policy = &backgroundPolicy
 	streams, _, buf, _ := genericclioptions.NewTestIOStreams()
 	cmd := NewCmdDelete(tf, streams)
 	cmd.Flags().Set("namespace", "test")