Fix option value for adding and editing volunteer roles to it hides unneeded properties

... and also so it hides / auto-assigns Value field as INT.

Check out some of the conditionals on option values forms like Phone Type.
... /civicrm/admin/options/phone_type?group=phone_type&action=add&reset=1

(only label, description and weight are exposed)
hopefully we can do this with hook(s) ???