Add ceph service slack_by_cc_service receiver

[databus23]

Looking at the receiver it seems this only works for non qa regions.
What do I need to do also get the alerts for qa in a dedicated slack channel?

[richardtief]

Only support_groups get their QA notifications posted in the Slack channel (without info alerts). ref The service owner usually does not want QA notifications in their channels as they can get quite noisy.
Solutions:

1. use the support group correctly
2. use Greenhouse Supernova Dashboard filtered by QA and Service