RabbiMQ validation: Hard dependency on package manager for version check

[phoenix-bjoern]

During deployment the RabbitMQ version gets validated. This is done by dpkg -s rabbitmq-server | grep Version. This adds a hard dependency on a) Debian package manager (excluding RHEL/CentOS and container setups) and b) an installation of RabbitMQ on the web server, which in high scale setups usually runs on a separate server/container.

While the version check outputs only a warning, the version check can be implemented in a better way in PHP (see #804).

[BaDos]

It will be done with #804

[BaDos]

The internal task MCLOUD-8940 was created