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