Use `kubectl delete all` in restore instructions

docs/maintenance.rst

@@ -103,10 +103,7 @@ the following commands:
 
    flux suspend kustomization $app
    flux suspend helmrelease -n stackspin-apps $app
-   kubectl delete service -n stackspin-apps -l stackspin.net/backupSet=$app
-   kubectl delete deployment -n stackspin-apps -l stackspin.net/backupSet=$app
-   kubectl delete statefulset -n stackspin-apps -l stackspin.net/backupSet=$app
-   kubectl delete persistentvolumeclaim -n stackspin-apps -l stackspin.net/backupSet=$app
+   kubectl delete all -n stackspin-apps -l stackspin.net/backupSet=$app
    velero restore create arbitrary-name-of-restore-operation --from-backup=$backup -l stackspin.net/backupSet=$app
    # At this point, please first wait for the restore operation to finish, see
    # text below.