Updating EndpointSliceMirroring controller to copy labels from Endpoints

The KEP specifies that the controller will "mirror all labels from the
Endpoints resource and all endpoints and ports from the corresponding subset".
I'd missed that in my initial implementation, this should fix that.

pkg/controller/endpointslicemirroring/utils.go

@@ -88,10 +88,7 @@ func newEndpointSlice(endpoints *corev1.Endpoints, ports []discovery.EndpointPor
 	ownerRef := metav1.NewControllerRef(endpoints, gvk)
 	epSlice := &discovery.EndpointSlice{
 		ObjectMeta: metav1.ObjectMeta{
-			Labels: map[string]string{
-				discovery.LabelServiceName: endpoints.Name,
-				discovery.LabelManagedBy:   controllerName,
-			},
+			Labels:          map[string]string{},
 			OwnerReferences: []metav1.OwnerReference{*ownerRef},
 			Namespace:       endpoints.Namespace,
 		},
@@ -100,6 +97,13 @@ func newEndpointSlice(endpoints *corev1.Endpoints, ports []discovery.EndpointPor
 		Endpoints:   []discovery.Endpoint{},
 	}
 
+	for label, val := range endpoints.Labels {
+		epSlice.Labels[label] = val
+	}
+
+	epSlice.Labels[discovery.LabelServiceName] = endpoints.Name
+	epSlice.Labels[discovery.LabelManagedBy] = controllerName
+
 	if sliceName == "" {
 		epSlice.GenerateName = getEndpointSlicePrefix(endpoints.Name)
 	} else {