Part/leave rooms after archive is not checked for a while

In my opinion the `@archive:matrix.org` bot shouldn't stay in rooms it joins for all eternity like is it's current behaviour.

If not for other reason, to avoid Denial of Service towards matrix-appservice-irc users when encountering IRC side limits and thus triggering privacy filter. https://github.com/matrix-org/matrix-appservice-irc/issues/1474#issuecomment-913025682

The issue names no files, tests, or entry points; start by tracing how the @archive:matrix.org bot joins and tracks rooms in this repository. Review the linked matrix-appservice-irc discussion for context, then define done as the bot parting or leaving archived rooms promptly enough to avoid the reported IRC-side limits.

Written by the indexing model from the issue text.