Fix duplication in historic appointment routes
Fix duplication in historic appointment routes

Past foreign secretaries doesn't need to have a constraint in the
regular historic_appointments controller, as it's served entirely as
hard-coded views.

This was originally duplicated in
23636d839e6439114213cba0e446ac551eccc84a.

YOTOV-LIMITED/whitehall,askl56/whitehall,alphagov/whitehall,ggoral/whitehall,robinwhittleton/whitehall,hotvulcan/whitehall,robinwhittleton/whitehall,ggoral/whitehall,askl56/whitehall,robinwhittleton/whitehall,hotvulcan/whitehall,ggoral/whitehall,hotvulcan/whitehall,YOTOV-LIMITED/whitehall,askl56/whitehall,YOTOV-LIMITED/whitehall,robinwhittleton/whitehall,ggoral/whitehall,alphagov/whitehall,askl56/whitehall,alphagov/whitehall,hotvulcan/whitehall,alphagov/whitehall,YOTOV-LIMITED/whitehall