Merge branch 'aregnery/admin-overview-polish' into 'master'

Polish the instance overview cards

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/167696



Merged-by: Simon Knox <simon@gitlab.com>
Approved-by: Sascha Eggenberger <seggenberger@gitlab.com>
Approved-by: Panos Kanellidis <pkanellidis@gitlab.com>
Approved-by: Anastasia Khomchenko <akhomchenko@gitlab.com>
Approved-by: Simon Knox <simon@gitlab.com>
Reviewed-by: Simon Knox <simon@gitlab.com>
Reviewed-by: Austin Regnery <aregnery@gitlab.com>
Reviewed-by: Vamsi Vempati <vvempati@gitlab.com>
Reviewed-by: Sascha Eggenberger <seggenberger@gitlab.com>
Reviewed-by: Anastasia Khomchenko <akhomchenko@gitlab.com>
Co-authored-by: Austin Regnery <aregnery@gitlab.com>