placing multiple holds: ignore num_copies when it's not allowed

[Galen Charlton]

When a user who is not allowed to place duplicate holds (see bug 1694058) nonetheless decides to pass a num_copies parameter to the hold request form, Evergreen will correctly only place one hold request. However, it does so by placing the first hold, then attempting to place the rest and getting bounced each time. The feedback page then displays that one hold has been placed and a bunch of "User already has an open hold on the selected item" failures.

It would be better if num_copies were simply ignored if the user does not have the requisite permission.

Evergreen master