MagmaKVStore - Stat doc not recreated after collection resurrection

Found with NexusKVStore - MB-47604.

The first flush to a dropped collection after a collection resurrection results in no stat doc being persisted for the given collection. Looks like the stats correct themselves on the next updated to the collection, but if we restarted then they'd be incorrect afterwards and the item count and disk sizes would potentially underflow.

I think we need to move the meta update that deletes the stats doc to before the persisting of the stats doc (if appropriate) to ensure that we don't "create" then delete where we should logically be deleting then creating it.