RMQ: Follow new sepia standard for routing-key

At the time of writing the routing key was merely a suggestion, it has
now been integrated into the sepia standard:
https://github.com/eiffel-community/eiffel-sepia/issues/8
https://eiffel-community.github.io/eiffel-sepia/rabbitmq-message-broker.html

Ensure that we follow the new format for the routing-key.

Solves: Jira GER-1697
Change-Id: Ied68582dc8c2a11c2ec174bc177db342184dc2d3