[lib] Restart BaseAutoJoinCommunityHandler when FID changes

Summary:
This diff addresses ENG-9539.

Depends on D13627

Test Plan: To be honest, I haven't tested this... I think the change is pretty predictable and safe

Reviewers: varun

Reviewed By: varun

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D13628