Exposing role for roulette

This way we can find where a test automation engineer is assigned to.

This will be used in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28678

See:

• https://gitlab.com/gitlab-org/quality/team-tasks/issues/128#note_170783578
• https://gitlab.com/gitlab-org/gitlab-ce/issues/62015