Render hook template lookup doesn't always fallback to other output format variants

[bep]

I found this debugging an issue with #9316.

I have a failing test case for this, but it's a little hard to explain. It should be rare, but it became visible with the new table render hooks, where we don't have any Goldmark defaults to fall back on.

[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.