Merge branch 'danmh-super-sidebar-flyout-polish' into 'master'

UI polish of super sidebar flyout menu

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/128104



Merged-by: Simon Knox <simon@gitlab.com>
Approved-by: Stanislav Lashmanov <slashmanov@gitlab.com>
Approved-by: Simon Knox <simon@gitlab.com>
Approved-by: Austin Regnery <aregnery@gitlab.com>
Reviewed-by: Dan Mizzi-Harris <dmizzi-harris@gitlab.com>
Co-authored-by: danmh <dmizzi-harris@gitlab.com>