Ping Release Managers on deployment check message

#1241 (closed) introduced deployment check messages if a deployment to prod is on-going and if there are active incidents or if something is wrong with the health status

Messages can be a bit noisy, so we decided to remove the release-managers mention from the initial message, as a consequence the message can go unnoticed by release managers.

Let's use this issue to discuss if the release-managers handle should be added back to the deployment check message.