JIRA: https://jira.spring.io/browse/INT-4482
The outer try/catch sends an `ErrorMessage` for all exceptions; it should
only do so for `MessageConversionException`. Integration flow exceptions
will have been already handled by `MessageProducerSupport`.
Also, populate the raw message header consistently - previously it only
was populated for flow exceptions. Although the LEFE contains the raw
message, it should be in the `ErrorMessage` header for consistency.
**cherry-pick to 5.0.x, 4.3.x**
* Polishing - PR Comments
88120a667e