Simplify CLI command to enable feature flags

Since we bumped the minimum supported RabbitMQ version to v3.9.0 in
#1110, we can use the
CLI command `rabbitmqctl enable_feature_flag all` introduced in
rabbitmq/rabbitmq-server@ce65586.

controllers/reconcile_cli.go

@@ -68,7 +68,7 @@ func (r *RabbitmqClusterReconciler) runRabbitmqCLICommandsIfAnnotated(ctx contex
 func (r *RabbitmqClusterReconciler) runEnableFeatureFlagsCommand(ctx context.Context, rmq *rabbitmqv1beta1.RabbitmqCluster, sts *appsv1.StatefulSet) error {
 	logger := ctrl.LoggerFrom(ctx)
 	podName := fmt.Sprintf("%s-0", rmq.ChildResourceName("server"))
-	cmd := "set -eo pipefail; rabbitmqctl -s list_feature_flags name state stability | (grep 'disabled\\sstable$' || true) | cut -f 1 | xargs -r -n1 rabbitmqctl enable_feature_flag"
+	cmd := "rabbitmqctl enable_feature_flag all"
 	stdout, stderr, err := r.exec(rmq.Namespace, podName, "rabbitmq", "bash", "-c", cmd)
 	if err != nil {
 		msg := "failed to enable all feature flags on pod"

controllers/reconcile_cli_test.go

@@ -60,7 +60,7 @@ var _ = Describe("Reconcile CLI", func() {
 					return sts.ObjectMeta.Annotations
 				}, 5).ShouldNot(HaveKey("rabbitmq.com/createdAt"))
 				Expect(fakeExecutor.ExecutedCommands()).To(ContainElement(command{"bash", "-c",
-					"set -eo pipefail; rabbitmqctl -s list_feature_flags name state stability | (grep 'disabled\\sstable$' || true) | cut -f 1 | xargs -r -n1 rabbitmqctl enable_feature_flag"}))
+					"rabbitmqctl enable_feature_flag all"}))
 			})
 		})
 	})