Merge pull request #58760 from mtaufen/kc-remove-kubeletconfigfile-gate

Automatic merge from submit-queue. 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>.

Removal of KubeletConfigFile feature gate: Step 1

This feature gate was redundant with the `--config` flag, which already
enables/disables loading Kubelet config from a file.

Since the gate guarded an alpha feature, removing it is not a violation
of our API guidelines.

Some stuff in `kubernetes/test-infra` currently sets the gate,
so removing will be a 3 step process:
1. This PR, which makes the gate a no-op.
2. Stop setting the gate in `kubernetes/test-infra`.
3. Completely remove the gate (this PR will get the release note).

```release-note
NONE
```

pkg/features/kube_features.go

@@ -39,6 +39,7 @@ const (
 
 	// owner: @mtaufen
 	// alpha: v1.8
+	// This gate is now a no-op. It will be removed shortly.
 	KubeletConfigFile utilfeature.Feature = "KubeletConfigFile"
 
 	// owner: @pweil-
@@ -241,7 +242,7 @@ func init() {
 var defaultKubernetesFeatureGates = map[utilfeature.Feature]utilfeature.FeatureSpec{
 	AppArmor:                                    {Default: true, PreRelease: utilfeature.Beta},
 	DynamicKubeletConfig:                        {Default: false, PreRelease: utilfeature.Alpha},
-	KubeletConfigFile:                           {Default: false, PreRelease: utilfeature.Alpha},
+	KubeletConfigFile:                           {Default: false, PreRelease: utilfeature.Alpha}, // KubeletConfigFile is now a no-op gate on the path to removal.
 	ExperimentalHostUserNamespaceDefaultingGate: {Default: false, PreRelease: utilfeature.Beta},
 	ExperimentalCriticalPodAnnotation:           {Default: false, PreRelease: utilfeature.Alpha},
 	Accelerators:                                {Default: false, PreRelease: utilfeature.Alpha},