fix: update dropdown headers to use strong text color

mentioned in commit 3c2258ce

mentioned in merge request gitlab-org/editor-extensions/gitlab-jetbrains-plugin!1102 (merged)

mentioned in merge request status-page!903

mentioned in merge request gitlab!168179 (merged)

mentioned in merge request gitlab-org/editor-extensions/gitlab-jetbrains-plugin!1103 (closed)

mentioned in merge request gitlab!168368 (closed)

mentioned in merge request gitlab-org/editor-extensions/gitlab-jetbrains-plugin!1105 (merged)

mentioned in merge request gitlab!168414 (merged)

mentioned in merge request gitlab-org/frontend/playground/accessibility-scanner!55 (closed)

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!352 (merged)

mentioned in merge request gitlab-org/frontend/playground/accessibility-scanner!58 (merged)