ci(craft): Only wait on GCB and nothing else (#20794)

Because GitHub actions does weird stuff with build statuses.

.craft.yml

@@ -7,6 +7,9 @@ changelog: CHANGES
 changelogPolicy: auto
 statusProvider:
   name: github
+  config:
+    contexts:
+      - 'onpremise-builder (sentryio)'
 targets:
   - name: github
   - name: pypi