Ensure all Redis-backed caching has a timeout or pruning logic

[TLSM]

At time of fork, it was part of the semi-frequent maintenance process to delete every key in Redis. This is because some uses of flask-caching did not have cache timeouts set. Or, for places like the logged-in counter that store data directly, were not pruning old entries.

Redis will soon be persisted across restarts, and this issue is timely and likely needs resolved within a couple weeks before performance issues accumulate (diagnosable by a sampling profiler spending >20% time in json.loads).