Merge branch 'eduardosanz/default-color-mode-option' into 'master'

Add default_color_mode option

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/183534



Merged-by: Erick Bajao <fbajao@gitlab.com>
Approved-by: Erick Bajao <fbajao@gitlab.com>
Co-authored-by: Eduardo Sanz García <esanz-garcia@gitlab.com>