poule: add rebuild/* to rebuild all at once

Signed-off-by: Arnaud Porterie (icecrime) <arnaud.porterie@docker.com>

poule.yml

@@ -44,6 +44,13 @@
 - triggers:
       pull_request: [ labeled ]
   operations:
+      - type:       rebuild
+        settings: {
+            # When configurations are empty, the `rebuild` operation rebuilds all the currently
+            # known statuses for that pull request.
+            configurations: [],
+            label:          "rebuild/*",
+        }
       - type:       rebuild
         settings: {
             configurations: [ arm ],