Merge branch...

Merge branch '520093-hide-prefill-variables-in-manual-job-ui-when-variables-are-disabled-2' into 'master' 

Hide prefill-variables in Manual job UI when variables are disabled

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/183068



Merged-by: Laura Montemayor <lmontemayor@gitlab.com>
Approved-by: Sunjung Park <spark@gitlab.com>
Approved-by: Briley Sandlin <bsandlin@gitlab.com>
Approved-by: Laura Montemayor <lmontemayor@gitlab.com>
Reviewed-by: Anna Vovchenko <avovchenko@gitlab.com>
Reviewed-by: Briley Sandlin <bsandlin@gitlab.com>
Co-authored-by: Anna Vovchenko <avovchenko@gitlab.com>