Sequence:

1. Migration finishes committing.
2. Migration updates rangeDeleter doc to remove pending flag.
3. OpObserver captures update and calls submitRangeDeletionTask, which sends a task to the arbitraryExecutor.
4. Migration main thread calls CSR::waitForClean
5. MetadataManager::trackOrphanedDataCleanup returns nothing since the range delete task has not yet been queued. Migration thread treats this as deletion being completed.
6. Migration main thread returns.
7. Actual range deletion task submitted in step#3 gets executed and queues orphan deletion.