* fix FK violation when inserting rows into `notifications_deliveries`
* add test for FK violation when inserting into notifications_deliveries
* sqlx prepare
* add migration to prevent stale notifications from being dequeued all at once upon fix
* Revert "add migration to prevent stale notifications from being dequeued all at once upon fix"
This reverts commit 446f398752bbddb632196a549501f9ce0b2da67f.