Merge branch 'slashmanov/page_specific_merge_requests_scss' into 'master'

Extract merge_requests.scss into page specific CSS

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/127117



Merged-by: drew stachon <730684-drew@users.noreply.gitlab.com>
Approved-by: Artur Fedorov <afedorov@gitlab.com>
Approved-by: drew stachon <730684-drew@users.noreply.gitlab.com>
Approved-by: Tristan Read <tread@gitlab.com>
Co-authored-by: Stanislav Lashmanov <slashmanov@gitlab.com>