Rejoining community fails on E2E tests

[leblowl]

I was able to get this to happen several times, but then I stopped being able to reproduce it. During the E2E tests, after leaving the community and rejoining, the app would get stuck on the invitation link page with a spinning icon. During the latest run I found in the logs that it looked like it didn't fully leave the community successfully and was still stuck awaiting OrbitDB to close. At the very least, we can make the LEAVE_COMMUNITY call an emitWithAck (synchronous) so that we do not allow a user to join a community if they weren't able to leave successfully.