Trace how much work is being done while "recursively fetching redactions"

[MadLittleMods]

Trace how much work is being done while "recursively fetching redactions"

Spawning from observing this trace for a /messages request (RoomMessageListRestServlet). We don't know if it took a while for the database to fetch a single redaction or a whole chain of redactions.

Pull Request Checklist

• Pull request is based on the develop branch
• Pull request includes a changelog file. The entry should:
  • Be a short description of your change which makes sense to users. "Fixed a bug that prevented receiving messages from other servers." instead of "Moved X method from EventStore to EventWorkerStore.".
  • Use markdown where necessary, mostly for code blocks.
  • End with either a period (.) or an exclamation mark (!).
  • Start with a capital letter.
  • Feel free to credit yourself, by adding a sentence "Contributed by @github_username." or "Contributed by [Your Name]." to the end of the entry.
• Code style is correct (run the linters)

[MadLittleMods]

Thanks for the review @anoadragon453 🐜