This ticket only deals with the sharding part of upgrade/downgrade (that is, _configsvrSetFeatureCompatibilityVersion), not the upgrade/downgrade on a replica set or single mongod (done through setFeatureCompatibilityVersion).

The cluster upgrade behavior should already ensure UUIDs are persisted in config.collections for all sharded collections, and that shards' notion of a sharded collection's UUID matches what's in config.collections.

This ticket is to test this behavior by inducing a failed upgrade (or downgrade), resuming upgrade (or downgrade) or initiating downgrade (or upgrade) afterwards and ensuring the UUIDs across the cluster are consistent.