SB caching

Service Bus connection caching: people who wait 10+ minutes lose the ability to send messages in Lab 5.
Workaround (from a learner):
Add the cache disability to the code. It works better this way. In PetClinicVisitRequestSender you add an import org.springframework.jms.connection.CachingConnectionFactory; and then :
CachingConnectionFactory connectionFactory = (CachingConnectionFactory) jmsTemplate.getConnectionFactory();
connectionFactory.setCacheProducers(false);
Workaround links:
- https://stackoverflow.com/questions/64917959/azure-service-bus-javax-jms-illegalstateexception-the-messageproducer-was-close
- https://stackoverflow.com/questions/59248234/azure-service-bus-amqp-idle-timeout-condition-amqplinkdetach-forced