Can we eliminate the memcached store of the lock component? Memcached is notorious for evicting keys that aren't even to their exptime because they are LRU (less recently used) than something else in the same slab class. By having the memcached store in the lock component, developers will trust it more than they should. It's great as a cache, but really shouldn't be used as a persistent concurrent locking mechanism. Thoughts?

Reference: #21093