Bug 31179: Don't copy invisible subfields when duplicating items

Bug 31179: Don't copy invisible subfields when duplicating items

Duplicate item is intended to duplicate the visible cataloging fields of an item, however,
currently it is duplicating the complete internal record of the item

To recreate:
1 - find an item in Koha staff client, copy the barcode
2 - Issue this item to a patron
3 - Return to the record
4 - Edit items
5 - Click 'Actions->Duplicate' for the item in question
6 - Save the item
7 - Note in the items table above for that 'Total checkouts' 'Due date'
 etc. have not been copied to new item

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>