usagestats: use a temporary redis for tests

Created by: keegancsmith

Hardcoding that redis is running locally is not needed. We can just start up redis ourselves. This might break users who only run redis via docker and do not have it installed. However, I think the benefit of this approach is worth them brew installing redis.

We should consider using a unix socket for redis even for our dev environment. Starting up redis ourselves would simplify the requirements on a users dev environment further.