Danger: Make Reviewer Roulette message more concise

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/143521



Merged-by: Jennifer Li <jli@gitlab.com>
Approved-by: Daniel Croft <dcroft@gitlab.com>
Approved-by: Jennifer Li <jli@gitlab.com>
Co-authored-by: Peter Leitzen <pleitzen@gitlab.com>