Suppress status unset in cmdDel

This change stops to update status in CNI's DEL command.
There are two reasons:

1. cmd DEL is invoked at only pod deletion, hence k8s does not
guarantee the pod and it may be already deleted. Hence this
API may failed.

2. In stateful set's pod recreation case, it may have race
condition to update the status at cmd DEL case.
In stateful set case, same pod name, i.e. stateful-0, is deleted
and then created again. In this case, if old Pod's CNI DEL command
is not finished before new Pod's creation, then SetStatus function
is failed due to pod UID mismatch.

pkg/multus/multus.go

@@ -919,21 +919,6 @@ func CmdDel(args *skel.CmdArgs, exec invoke.Exec, kubeClient *k8s.ClientInfo, po
 		}
 	}
 
-	// unset the network status annotation in apiserver, only in case Multus as kubeconfig
-	if kubeClient != nil {
-		if !skipStatusUpdate {
-			if !types.CheckSystemNamespaces(string(k8sArgs.K8S_POD_NAMESPACE), in.SystemNamespaces) {
-				err := k8s.SetNetworkStatus(kubeClient, k8sArgs, nil, in)
-				if err != nil {
-					// error happen but continue to delete
-					logging.Errorf("Multus: error unsetting the networks status: %v", err)
-				}
-			}
-		} else {
-			logging.Debugf("WARNING: Unset SetNetworkStatus skipped")
-		}
-	}
-
 	e := delPlugins(exec, pod, args, k8sArgs, in.Delegates, len(in.Delegates)-1, in.RuntimeConfig, in)
 
 	// Enable Option only delegate plugin delete success to delete cache file