Fix PlatformTransactionManager auto-binding for Rabbit

[snicoll]

#3222 introduced a regression as Rabbit does not support JTA (contrary to JMS) so a different fix should be applied there.

Rabbit also has a channelTransacted flag that we could use

[snicoll]

I vote for switching the check on RabbitTransactionManager and add channelTransacted if it is not set (for consistency with the JMS part). This clearly means that users who want a local data store to run as part of the processing of a message should add @Transactional on their @RabbitListener method (or anything that's actually being called by that method.

I wouldn't expose the channelTransacted flag as it is quite dependent of the transaction manager configuration anyway. Non-transactional listeners can be set by creating their own factory after all.

[dsyer]

I removed the transaction manager completely from the rabbit container (user can create one explicitly if he wants it). For 1.3 we could extend the configurability. From @garyrussell:

This is what they exposed in the CF tile for the xd rabbit bus: ackMode, concurrency, maxConcurrency, prefetch, and txSize.