fix(GlCollapsibleListbox, GlDisclosureDropdown): Update group border color

mentioned in commit 1ed5a284

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!213 (merged)

mentioned in merge request gitlab!133385 (merged)

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!215 (merged)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!3561 (merged)

mentioned in merge request gitlab-docs!4304 (merged)

mentioned in merge request gitlab!133776 (merged)

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!218 (closed)

mentioned in merge request status-page!881 (merged)

mentioned in merge request status-page!883 (merged)