Merge branch 'add-admin_cicd_variables-custom-permission' into 'master'

Add admin_cicd_variables custom ability

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/143369



Merged-by: Rutger Wessels <rwessels@gitlab.com>
Approved-by: Simon Tomlinson <stomlinson@gitlab.com>
Approved-by: Jarka Košanová <jarka@gitlab.com>
Approved-by: Smriti Garg <sgarg@gitlab.com>
Reviewed-by: Jarka Košanová <jarka@gitlab.com>
Reviewed-by: Alex Buijs <abuijs@gitlab.com>
Co-authored-by: Alex Buijs <abuijs@gitlab.com>