Use Rails 5.2 Redis caching store

This is the first step in providing a fault-tolerant and distributed
Redis caching store. We disable compression to avoid introducing a
change that could have an adverse effect in production.

Note that we won't be able to take advantage of the fault-tolerance and
distributed features yet until we solve
https://gitlab.com/gitlab-org/gitlab-ce/issues/64829.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/64794