The sharded collection config.system.sessions should be cloned during setFCV(9.0).

Because this collection belongs to the `config` database, it is not clear if we are going to clone its collection metadata or not. Note: The `config` database is not registered in `config.databases`.

Moreover, I think we are not catching this issue via checkMetadataConsistency because `config` is skipped.

We should investigate this.