Today whenever a DDL has to happen on a collection on a sharded cluster we acquire the critical section for it. This prevent reading inconsistent metadata states while modifying the sharding metadata.

However, the temporary resharding collection does not follow this protocol and as a result can lead to a temporarily inconsistent sharding state that has no effect on the final result but could lead to undefined behaviour if something were to rely on it being consistent during the resharding operation. This is mostly fine today since modifications to the temporary collection are always paired with the critical section of the source collection and are thus temporary until the resharding operation finishes.

This ticket is about making the temporary collection follow the same protocol as other collections and taking it for every DDL that affects it.