feat(css): add gl-w-30

mentioned in commit 5de90c70

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!116 (merged)

mentioned in merge request status-page!684 (merged)

mentioned in merge request gitlab!109720 (merged)

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!119 (merged)

mentioned in merge request gitlab-docs!3484 (merged)

mentioned in merge request gitlab-docs!3486 (merged)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!3231 (merged)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!3232 (merged)