Clean up visitor types
https://tickets.ch.cam.ac.uk/rt/Ticket/Display.html?id=206041
@kjp45 says:
Also, in discussion with Rachael, there are other categories which could be deleted as are no longer used:
Consultant
Visitor long stay
Visitor short stay
Undergraduate
We could either do this by disabling them in the hid view (if this feature works in Hotwire) or by a cleanup of old data and removal of the rows