remove noop std::move from CollectionCatalog::setCollectionNamespace() rollback handler

This std::move in the RecoveryUnit rollback handler has no effect on the movable type NamespaceString 'fromCollection' because 'fromCollection' is captured as a const variable in the lambda. In addition to removing the confusing std::move, this would also be a good opportunity to add some unit test coverage for the rollback handler.