Investigate consistent hashing for memcache

[weeco]

We should investigate and clarify whether and under what circumstances it makes sense to enable or disable the consistent hashing feature for Memcache. From the memcache docs:

Consistent Hashing is a model that allows for more stable distribution of keys given addition or removal of servers. [...]

https://github.com/memcached/memcached/wiki/ConfiguringClient#consistent-hashing

We have flags to enable it:

-memcached.consistent-hash=true
-store.index-cache-read.memcached.consistent-hash=true

I am not sure on what cortex components this should be enabled and how the migration from non consistent hashing to consistent hashing works. Can we just switch this without worrying about that, or should we clear the cache after enabling this?