The MetadataManager must see every chunk range change (add/remove) to the active CollectionMetadata it maintains because the MetadataManager will be responsible for initiating range deletion and must maintain an accurate rangesToClean data structure.

For example, currently the MigrationSourceManager calls CollectionMetadata::cloneMigrate with the ScopedCollectionMetadata it gets from the MetadataManager. The MetadataManager does not currently update its rangesToClean when this happens.

Note: We may need to implement this, but temporarily comment out the line that actually adds/removes the range from rangesToClean. Until the the new CollectionRangeDeleter is committed and replaces the current RangeDeleter, the rangesToClean data structure would just grow larger and larger and never be reduced by a CollectionRangeDeleter.