Merge branch 'add-services-variables-to-ci-yaml' into 'master'

Add `services:variables` to CI schema

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/112025



Merged-by: Frédéric Caplette <fcaplette@gitlab.com>
Approved-by: Frédéric Caplette <fcaplette@gitlab.com>
Approved-by: Marcel Amirault <mamirault@gitlab.com>
Reviewed-by: Mireya Andres <mandres@gitlab.com>
Co-authored-by: Mireya Andres <mandres@gitlab.com>
Co-authored-by: Marcel Amirault <mamirault@gitlab.com>