For authenticated users that are not global staff, changing discussion providers after a course has started fails with 403 Forbidden. Related issues: * [BB-4253](https://tasks.opencraft.com/browse/BB-4253) * [TNL-8142](https://openedx.atlassian.net/browse/TNL-8142) BREAKING CHANGE: Course staff, who were previously allowed to do this operation, will instead receive a 403 Forbidden response.