Move CSS Classes `tab-width-X` from `utilities.scss` to `app/assets/stylesheets/framework/layout.scss`

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/170689



Merged-by: Peter Hegman <phegman@gitlab.com>
Approved-by: Peter Hegman <phegman@gitlab.com>
Co-authored-by: Sujal Gupta <sujalgupta6100@gmail.com>