feat(Tailwind): use border default design token for border classes

mentioned in commit d9d98f18

mentioned in merge request gitlab-org/editor-extensions/gitlab-jetbrains-plugin!920 (merged)

mentioned in merge request status-page!903

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!4039 (merged)

mentioned in merge request gitlab!165456 (closed)

mentioned in merge request gitlab!165458 (merged)

mentioned in commit bb2d7467

mentioned in merge request gitlab!165726 (merged)

mentioned in merge request gitlab!166177 (merged)

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!348 (merged)

mentioned in merge request gitlab-org/frontend/playground/accessibility-scanner!50 (merged)

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!349 (merged)

mentioned in merge request gitlab-org/frontend/playground/accessibility-scanner!51 (merged)