JIRA: https://jira.spring.io/browse/INT-4509
To avoid a re-usage of the `AbstractReplyProducingMessageHandler`,
the `IntegrationFlowDefinition` and `AbstractStandardMessageHandlerFactoryBean`
have a `static Set<>` to store already used producers and check it for
newly provided.
These stores are not cleaned when beans are destroyed leading to memory
leaks
* Implements a `DisposableBean` for the `AbstractStandardMessageHandlerFactoryBean`
to remove its `replyHandler` from the `referencedReplyProducers` on
`destroy()`
* Introduce a `IntegrationFlowDefinition.ReplyProducerCleaner` - an
`DestructionAwareBeanPostProcessor` to clean up removing `MessageProducer`
from the `IntegrationFlowDefinition.REFERENCED_REPLY_PRODUCERS`
**Cherry-pick to 5.0.x**
da977941f8