Use MemoryCacheInterface for cache.tfa_memache

Problem/Motivation

Was reminded that I had seen this an wanted to investigate tightening down TFA.

There is a MemoryCacheInterface in Core that we could potentially use instead of CacheBackendInterface for the cache.tfa_memcache injected service to reduce (though not 100% eliminate) the chance of a persistent cache backend being swapped in.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes