Track artifact:report:junit keyword usage

I am trying to get data on what% of GitLab CI pipelines run unit tests.

believe the clearest signal is a presence of artifact:reports:junit - Can we add this as a keyword to track with the mechanism suggested in (#404563 (comment 2834423543)) and we can review the findings in 2 weeks.

We do have https://metrics.gitlab.com/keys/service-ping/?q=redis_hll_counters.testing.i_testing_active_user_monthly but looks like it's based only if the user uploads a test report or coverage report which doesn't really indicate the true usage of pipelines running unit test.