Fix incorrect handling of transactions using deferred constraints

[simPod]

doctrine#6543 partially solved what we tried to achieve in doctrine#4846. With that There's no active transaction exception contains the actual exception in $previous.

Now, let's get rid of There's no active transaction exception which occurs e.g. when using deferred constraints so the violation is checked at the end of the transaction and not during it.

The current faulty flow is following:

1. on commit(), Unique violation occurs
2. transaction is implicitly aborted in database
3. DBAL calls rollback()
4. Since there's no active transaction, There's no active transaction exception is thrown:

This PR adjusts the flow so:

1. on commit(), Unique violation occurs
2. transaction is implicitly aborted in database
3. DBAL DOES NOT call rollback() 🥳