K8SPXC: set controller reference for PiTR deployment (#1880)

Set controller reference for PiTR deployment the same way as it's set for PXC and proxy StatefulSets. This would crate a connection between PiTR deployment and cluster resource.

pkg/controller/pxc/backup.go

@@ -48,6 +48,10 @@ func (r *ReconcilePerconaXtraDBCluster) reconcileBackups(ctx context.Context, cr
 			if err != nil {
 				return errors.Errorf("get binlog collector deployment for cluster '%s': %v", cr.Name, err)
 			}
+			err = setControllerReference(cr, &binlogCollector, r.scheme)
+			if err != nil {
+				return errors.Wrapf(err, "set controller reference for binlog collector deployment '%s'", binlogCollector.Name)
+			}
 
 			currentCollector := appsv1.Deployment{}
 			err = r.client.Get(context.TODO(), types.NamespacedName{Name: binlogCollector.Name, Namespace: binlogCollector.Namespace}, &currentCollector)