Merge branch '519778-search-results-remove-custom-styles-from-author-dropdown' into 'master'

Apply style suggestions for dark mode rollout for author dropdown in global search

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/182590



Merged-by: Scott de Jonge <sdejonge@gitlab.com>
Approved-by: Dan MH <dmizzi-harris@gitlab.com>
Approved-by: Tomas Bulva <tbulva@gitlab.com>
Approved-by: Scott de Jonge <sdejonge@gitlab.com>
Reviewed-by: Dan MH <dmizzi-harris@gitlab.com>
Reviewed-by: Scott de Jonge <sdejonge@gitlab.com>
Co-authored-by: James Rushford <jrushford@gitlab.com>