Make chutney bridge authorities publish bridges in their networkstatus-bridges

This issue depends on the tor bridge descriptor upload fix in legacy/trac#33582 (moved), or robust reachability self-tests in legacy/trac#33222 (moved).

Chutney bridge authorities don't have any bridges in their networkstatus-bridges. That's a problem, because we want to check networkstatus-bridges for the reachability checks in legacy/trac#33232 (moved).

Once bridges upload their descriptors, we can make chutney check the bridge authority's networkstatus-bridges for bridge nicknames (this ticket).

We can only do the networkstatus-bridges check on tor versions with the legacy/trac#33222 (moved) or legacy/trac#33582 (moved) fixes. So we'll need to check for:

• the next tor 0.4.4-alpha version, or
• an environmental variable that enables these tests.

We don't have to do these fixes, because it should be enough to test relay reachability. But we would risk breaking bridge reachability tests, and not knowing about it until after a release.