Add notification for `schedule:package-and-qa` for Pipeline Triage Rotation

In !20268 (merged) schedule:package-and-qa was set to be allowed_fail which impacts the Pipeline Triage rotation.

After that change, there isn't a easy way to identify failures and take an action for downstream gitlab-qa pipeline failures. My steps I listed out for @zeffmorgan

  1. Navigate to https://gitlab.com/gitlab-org/gitlab/pipeline_schedules
  2. Open the last run of the scheduled pipeline
  3. Look at schedule:package-and-qa job

Simple proposal

Bring back notification to #qa-master which was removed with !18861 (merged)

@gl-quality/eng-prod - WDYT, how can we help our SDET teammates here?

Edited by Kyle Wiebers