1. 1. 1. Fix: forward fromMigrate flag through cross-database rename source drop

When a cross-DB rename is performed after moveCollection, the donor shard retains a ghost copy of the source collection. The rename coordinator's final step — dropping the source namespace via renameCollectionAcrossDatabases — was not forwarding the markFromMigrate flag down to dropCollectionForApplyOps, causing the internal cleanup drop to leak into the user-visible change stream as a spurious drop event.

The fix threads markFromMigrate through dropCollectionForApplyOps and its internal helpers so the oplog entry is correctly marked, filtering it from change streams. A regression test verifies the exact event sequence (create → insert → reshardCollection → drop) with no phantom second drop.