[IMP] product: barcode should not disappear on archiving product

Before this commit when a user archives the product, the barcode
field in its template used to get disappeared.

Since barcode field in template is a related field to product,
the field gets invisible in product template when the user archives
the related product.

After this commit, even when a product is archived,
its barcode will still be visible in template.

Here the barcode field is changed from related to computed.

task-1978559