feat(tabs): Remove theme color

mentioned in commit 4075f8a8

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!181 (closed)

mentioned in merge request status-page!842 (merged)

mentioned in merge request gitlab-docs!4123 (merged)

mentioned in merge request gitlab-docs!4124 (closed)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!3432 (merged)

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!182 (merged)

mentioned in merge request gitlab!128113 (closed)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!3479 (merged)

mentioned in merge request gitlab!126562 (merged)