SERVER-90360 introduced a new (and hopefully clearer and simpler) contract to help keep in-memory states with on-disk data.

The contract is:

ReplicaSetAwareInterface::onConsistentDataAvailable: In-memory states may choose to reconstruct here and
subscribe to future writes from now on (e.g. via OpObservers). This is called

• After replSetInitiate
• After initial sync completes (for both logical and file-copy based initial sync)
• After rollback to the stable timestamp
• After storage startup from a stable checkpoint
• After replication recovery from an unstable checkpoint

ReplicationCoordinator::isDataConsistent: In-memory state may start tailing writes (e.g. via OpObservers) when this returns true.

• Instead of checking member states, this function returns true after ReplicaSetAwareInterface::onConsistentDataAvailable is called.

This ticket is to determine if we should adopt this for VectorClockMongoD (See git grep SERVER-91505).