Notify Slack on triggered pipeline failures
This implements https://gitlab.com/gitlab-org/release/tasks/issues/618#note_129588644 and relates to https://gitlab.com/groups/gitlab-org/-/epics/692.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
This implements https://gitlab.com/gitlab-org/release/tasks/issues/618#note_129588644 and relates to https://gitlab.com/groups/gitlab-org/-/epics/692.