Remove deprecated kubectl drain flag

delete-local-data was deprecated back in v1.20 with this commit:
kubernetes@625e47a

It's about time we entirely drop the support for this flag. Users should
be already using delete-emptydir-data instead.

Author: soltysh

staging/src/k8s.io/kubectl/pkg/cmd/drain/drain.go

@@ -224,8 +224,6 @@ func NewCmdDrain(f cmdutil.Factory, ioStreams genericiooptions.IOStreams) *cobra
 	}
 	cmd.Flags().BoolVar(&o.drainer.Force, "force", o.drainer.Force, "Continue even if there are pods that do not declare a controller.")
 	cmd.Flags().BoolVar(&o.drainer.IgnoreAllDaemonSets, "ignore-daemonsets", o.drainer.IgnoreAllDaemonSets, "Ignore DaemonSet-managed pods.")
-	cmd.Flags().BoolVar(&o.drainer.DeleteEmptyDirData, "delete-local-data", o.drainer.DeleteEmptyDirData, "Continue even if there are pods using emptyDir (local data that will be deleted when the node is drained).")
-	cmd.Flags().MarkDeprecated("delete-local-data", "This option is deprecated and will be deleted. Use --delete-emptydir-data.")
 	cmd.Flags().BoolVar(&o.drainer.DeleteEmptyDirData, "delete-emptydir-data", o.drainer.DeleteEmptyDirData, "Continue even if there are pods using emptyDir (local data that will be deleted when the node is drained).")
 	cmd.Flags().IntVar(&o.drainer.GracePeriodSeconds, "grace-period", o.drainer.GracePeriodSeconds, "Period of time in seconds given to each pod to terminate gracefully. If negative, the default value specified in the pod will be used.")
 	cmd.Flags().DurationVar(&o.drainer.Timeout, "timeout", o.drainer.Timeout, "The length of time to wait before giving up, zero means infinite")

staging/src/k8s.io/kubectl/pkg/cmd/drain/drain_test.go

@@ -635,17 +635,6 @@ func TestDrain(t *testing.T) {
 			expectDelete:          true,
 			expectOutputToContain: "node/node drained",
 		},
-		{
-			description:           "Ensure compatibility for --delete-local-data until fully deprecated",
-			node:                  node,
-			expected:              cordonedNode,
-			pods:                  []corev1.Pod{jobPod},
-			rcs:                   []corev1.ReplicationController{rc},
-			args:                  []string{"node", "--force", "--delete-local-data=true"},
-			expectFatal:           false,
-			expectDelete:          true,
-			expectOutputToContain: "node/node drained",
-		},
 		{
 			description:           "Job-managed terminated pod",
 			node:                  node,