In add/remove shard suites (and also in config transition suites, though less problematically there due to the stability of the config server's shard id), the connCache's list of shards will become stale.

This ticket is to investigate replacing the connCache (at least the shard list portion) with topology discovery helpers or keeping the connCache updated as the add/remove shard hook executes.

We would like to know how much work this will be given that there are currently only 4 tests relying on the connCache that run in add/remove shard suites.