Disable tracking of security releases for now

Until Omnibus' workflow is moved to GitLab.com, security deployment tracking will not work. Instead of fixing this and refactoring all that in a week or two, we just disable the tracking for now.

changed milestone to %12.9

added security label

approved this merge request

merged

mentioned in commit 0bece901

mentioned in issue gitlab-com/gl-infra/scalability#190

mentioned in issue gitlab-com/gl-infra/delivery#692 (closed)

added typemaintenance label