Sandbox caching issues in the ratelimit code.
Review Request #13447 — Created Dec. 4, 2023 and submitted
If the cache server misbehaves, it can break API or authentication
calls, due to the rate limit code depending on the cache server.
We now sandbox these calls, logging errors when problems occur. This
effectively disables rate limiting, but helps ensure the service can
still be used.
Djblets and Review Board unit tests pass.