In the ShardServerOpObserver::onUpdates function, if we observe an update to config.rangeDeletions removing the "prepare" field, we should call CollectionShardingRuntime::cleanupRange for the range specified in the document.
We can test this independently with a jstest:
- Insert orphans directly into a shard
- Insert a document directly into config.rangeDeletions
- Assert that orphans eventually are removed.