Refactor clean up functions and related tests

I noticed these tests are timing out when I run them locally. I don't think adding so many users and bridges improves test coverage. While I was at it, I noticed a few optimizations for the clean up functions.

requested review from @onyinyang

assigned to @cohosh

This looks great. Thanks for taking this on. I think having only 5 bridges for each of the open entry and spare buckets is probably fine but note that with our current bridges/bucket this will result in only a single trusted bucket in the Lox authority (3 open-invite buckets and 1 trusted which is a superset of those 3) and 2 leftover. I don't think there's much potential for unexpected behaviour that we could sus out by adding additional buckets but just wanted to point that out in case you can think of anything.

approved this merge request

added 21 commits

• ec7384b4...f8923e2d - 14 commits from branch tpo/anti-censorship:main
• 2bfeeda0 - Remove extraneous check for expired blockages
• 9da930d9 - Use more descriptive variable name
• eeca574e - Remove unnecessary check before calling remove
• f56e6ecd - Overhaul test_clean_up_blocked
• bdb3438b - Remove extraneous check for expired open entries
• 823dd87d - Rename variable to be more descriptive
• f2c5f23b - Overhaul test_clean_up_open_entry

Compare with previous version

merged manually

mentioned in issue #70 (closed)