reconsider filing issues on empty repo

[jku]

Currently we have two workflows that file issues on failures on cron: online-signing and test.

This is a bit annoying when you create repo since not having a metadata/ directory is considered a failure... so the workflows start filing issues pretty much immediately.

We should consider options here:

1. workflows could just succeed if metadata does not exist in git at all
   • this would mean wiping the metadata would not lead to any visible failure...
   • but that might be ok since if you can wipe the metadata you can also wipe the workflows (and it is possible to setup alerts outside of the repo a la sigstore-probers)
2. alternatively we could mention in docs that actions can be disabled until the first signing event...
3. ???