[13.x] Don't swallow deadlocks in DatabaseLock inside a transaction - #61708

When the lock row insert hits a deadlock, acquire() catches it like any other insert failure and falls through to the update. If the lock shares a connection with an open transaction, MySQL has already rolled that transaction back. Laravel still thinks it's open, so the app keeps running with its earlier writes gone and later writes autocommitting.

This rethrows concurrency errors from the insert when the connection is inside a transaction, so DB::transaction() can roll back or retry like it does for any other deadlock. The prune and release queries only ignore concurrency errors outside a transaction now too, since they would leave the same broken state. Outside a transaction nothing changes.

Fixes #61707