MULE-7731 JMS transport should reuse javax.jms.Session, javax.jms.Messag...

...eProducer instances by default
Give the condition that existed in doDecorated previously the condition 'muleContext.getTransactionManager() != null' existed previsouly anyway.  I can add 'muleContext.getTransactionFactoryManager()' back in as an additional condition is we think this is required though.