SpringBoot The error message is unhelpful when spring.rabbitmq.host is configured with a comma-separated value

As discussed on issue #35628, at some point the host property accepted multiple comma-separated hosts. However, this was not intended, and for better clarification, it was decided to implement a clearer error message for this situation.

This PR adds an extra check in org.springframework.boot.autoconfigure.amqp.RabbitProperties#determineAddresses for commas in the host property, throwing an InvalidConfigurationPropertyValueException if any is found.

Comment From: mhalbritter

Thank you very much and congratulations on your first contribution :tada:!