AMQP-408 channelTransacted=true when txManager

JIRA: https://jira.spring.io/browse/AMQP-408

`SimpleMessageListenerContainer`: coerce `channelTransacted=true` when `transactionManager` is provided
True:
```
assertTrue((Boolean) ReflectionTestUtils.getField(container, "transactional"));
```
Copy/paste issue. Doh.