Remove backup label from MSA since it's backed up by default (#430)

Signed-off-by: fxiang1 <fxiang@redhat.com>
(cherry picked from commit 9d97ba734718964cc9e35a716311b2a7860ce7be)

Author: fxiang1

pkg/controller/spoketoken/spoke_token_controller.go

@@ -340,9 +340,6 @@ func (r *ReconcileAgentToken) createOrUpdateApplicationManagerSecret() (bool, er
 			ObjectMeta: v1.ObjectMeta{
 				Name:      appAddonName,
 				Namespace: r.syncid.Name,
-				Labels: map[string]string{
-					"cluster.open-cluster-management.io/backup": "",
-				},
 			},
 			Spec: authv1beta1.ManagedServiceAccountSpec{
 				Rotation: authv1beta1.ManagedServiceAccountRotation{