Run QA tests when a feature flag file is deleted

What does this MR do and why?

This follows up on https://gitlab.com/gitlab-org/quality/team-tasks/-/issues/987

It triggers package-and-qa-ff-deleted when a feature flag definition file is deleted. It runs a limited set of tests, as when a feature flag file is updated. However, it only runs the downstream pipelines in that one instance of package-and-qa since there is no feature flag to enable/disable.

Note that this also restores the original package-and-qa job for MRs that include a feature flag definition file, since the package-and-qa-ff-enabled and package-and-qa-ff-disabled jobs start pipelines that no longer include the full set of orchestrated tests. package-and-qa will be manual for most non-QA MRs, as it used to be.

See #341333 (closed)

Test results

The following table shows the state of each job in various types of MRs.

MR changes	package-and-qa	package-and-qa-ff-enabled	package-and-qa-ff-disabled	package-and-qa-ff-deleted
Deleted FF	manual	no downstream	no downstream	ee:instance jobs
Edited FF	manual	ee:instance jobs	ee:instance jobs	no downstream
Deleted FF + QA change	automatic, all jobs	no downstream	no downstream	ee:instance jobs
Edited FF + QA change	automatic, all jobs	ee:instance jobs	ee:instance jobs	no downstream
Deleted FF + Edited FF	manual	ee:instance jobs	ee:instance jobs	no downstream
Deleted FF + Edited FF + QA change	automatic, all jobs	ee:instance jobs	ee:instance jobs	no downstream

• "no downstream" means the job did not trigger the downstream pipelines.
• "ee:instance jobs" means that the downstream pipelines were triggered, but only included the ee:instance jobs, not the full set of jobs as in the original package-and-qa.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.