Consider removing GlobalIndexClonerState::kDone

https://github.com/10gen/mongo/blob/c9e875975a43c819387095033bdabff82cc9cb96/src/mongo/db/s/global_index/global_index_cloner.idl#L47

It is currently not a real state that gets written in the state document but used as a stand-in to represent state of being deleted in tests