Fixes: #9633
Issue link: https://github.com/spring-projects/spring-integration/issues/9633
The message flags of the received messages are outdated and don't contain the changes of `AbstractMailReceiver#setMessageFlags`,
because the flags are only applied to the original message and not the copy (`AbstractMailReceiver.IntegrationMimeMessage`).
* Call `setMessageFlagsAndMaybeDeleteMessages()` for `IntegrationMimeMessage` copies as well
(cherry picked from commit 1d85d6b43c)