Currently we remove the resharding state document as soon as we transition to done. The resharding improvements project introduced a quiesced state so that the resharding state document persisted for a period of time instead of deleting it right away. 

To simplify the state machine, we should remove the quiesced state and keep the state document in the done state for a set period of time, similar to what we do for the current quiesced state.

Besides simplifying the code this has the added bonus of keeping the state machine consistent, as there is some code that runs after we transition to done currently, but it is not guaranteed to run if we remove the doc and there is a failover.