[FIX] stock: do not allow to add product into processing wizard, it thro...

...ws integrity error because the locations are not displayed on partial lines which are required field, disabled adding lines in o2m, opw:612768

Do not allow to add products from wizard while processing picking. In v7, Location and Destination locations are not displayed on o2m field in wizard, and these locations are required field. So adding new product in o2m throws intergrity error. Disabled adding a new product in the o2m editable list.