Deprecate Alerts service metric
What does this MR do?
Alerts service was completely removed in %13.8: !50913 (merged), !53534 (merged).
This deprecates the alerts service metric from the usage ping.
I'm following this guide !59000 (merged) and created https://gitlab.com/gitlab-data/analytics/-/issues/8609 in the GitLab Data Team project.
Related to #297029 (closed)
Edited by Arturo Herrero