Allow slack service to send messages on different channels (!5124) · Merge requests · GitLab.org / GitLab FOSS · GitLab

closes #8110 (closed)

Allow slack service to send messages on different channels

Does this MR meet the acceptance criteria?

CHANGELOG entry added
Documentation created/updated
API support added
Tests
- Added for this feature/bug
- All builds are passing
Conform by the style guides
Branch has no merge conflicts with master (if you do - rebase it please)
Squashed related commits together