Fix App Push Test

[kamilzyla]

Problem

Our App Push Test stopped working after #573, as it relied on rhino-test.yml being run automatically on push to any branch.

Possible approaches

1. Forget about it and delete the test.
2. Add a step to app-push-test-.yml to trigger rhino-test.yml via GitHub CLI: gh workflow run rhino-test.yml --ref bot/app-push-test. Unfortunately the run name will be generic (when triggered automatically from push, it used the commit name).
3. Add bot/app-push-test branch trigger to rhino-test.yml (either in Rhino or in the test itself).