Display event creator on event detail page + Remove unused fs_event.bot

What does this MR do?

Split out some independent changes from the bigger !1717 (merged)

How confident are you it won't break things if deployed?

well...

Links to related issues

• preparatory work for !1717 (merged)

How to test

Create events and check their detail pages

Screenshots

Checklist

• added a test, or explain why one is not needed/possible...
• no unrelated changes
• asked someone for a code review
• set a "for:" label to indicate who will be affected by this change
• use "state:" labels to track this MR's state until it was beta tested
• added an entry to CHANGELOG.md
• add a short text that can be used in the release notes
• beta testing issue combined with !1717 (merged)

Release notes text

TODO