needs-rebase should be an external-plugin

config/prow/plugins.yaml

@@ -10,7 +10,6 @@ plugins:
       - help
       - heart
       - hold
-      - needs-rebase
       - label
       - lgtm
       - trigger
@@ -18,6 +17,13 @@ plugins:
       - wip
       - yuks
 
+external_plugins:
+  rocky-linux/peridot:
+    - name: needs-rebase
+      events:
+        - issue_comment
+        - pull_request
+
 config_updater:
   maps:
     config/prow/config.yaml: