JIRA: https://jira.spring.io/browse/INT-3888
Note sure yet what race condition we have in the `DefaultSubscriptionRegistry`,
but that looks for me better to follow with the standard `SubscriptionRegistry.findSubscriptions()`
to check subscription present, unless fail during `send()` because of `destinationLookup` early exit.
Fix for the `StompServerIntegrationTests`
Looks like we have to `reconnect()` for any `handleTransportError()` activity,
otherwise we are just hang in the Reactor's TCP reconnect loop without freeing resources
for other activities, e.g. start Embedded STOMP Broker.
Increase `receive` timeout in case of wait for the Broker Start
c0d1277b55