Draft: GitLab integration test for gitlab-org/gitlab-services/design.gitlab.com!5396

Prior to this change, the @gitlab/ui implementation of the GlCollapsibleListbox was less accessible to screen readers. Specifically, the toggle button was not announcing itself as a combobox. This role is required for an embedded listbox, and was flagged as an item for improvement.

Changelog: fixed

Issue: https://gitlab.com/gitlab-org/gitlab/-/issues/580011

Integration test merge request for gitlab-org/gitlab-services/design.gitlab.com!5396.

Checks

• The full Jest suite has run (i.e., not just predictive jobs)
• The full Jest suite has passed
• The full RSpec suite has run (i.e., not just predictive jobs)
• The full RSpec suite has passed