LMS Courseware access to Old Mongo courses was already removed in
fc8601de (https://github.com/openedx/edx-platform/pull/30172). This
commit makes direct links to the other tabs (progress, instructor
dashboard, discussion, static tabs) fail with a 404 error on Old
Mongo courses.
Upcoming work to remove parent/child relationships from the Old
Mongo Modulestore would have broken these pages anyway.