Symfony version(s) affected: 4.3

Description
The default for normal exchanges and queues is AMQP_DURABLE, see

But the delay exchange and queues are not created as durable by default. This is inconsistent and problematic because delayed messages are can stay for long the in queue. So when the server restarts those delayed messages are lost. For this reason it would also make sense to send messages to the delay exchange by default with delivery_mode=persistent.