[FIX] website_sale_digital: fixed attachment count
[FIX] website_sale_digital: fixed attachment count

The read_group function bypasses some restrictions, and in this case
was counting the "image", "image_small" and "image_medium" attachments
of the products, thus resulting in wrong attachment counts.

I changed it to a search_count which is cleaner, simplifies the code
a lot and, more importantly, returns the right values.

dfang/odoo,ygol/odoo,dfang/odoo,sysadminmatmoz/OCB,storm-computers/odoo,hip-odoo/odoo,ygol/odoo,dfang/odoo,microcom/odoo,optima-ict/odoo,dfang/odoo,optima-ict/odoo,optima-ict/odoo,bplancher/odoo,stephen144/odoo,Elico-Corp/odoo_OCB,dfang/odoo,microcom/odoo,ygol/odoo,bplancher/odoo,microcom/odoo,laslabs/odoo,optima-ict/odoo,storm-computers/odoo,storm-computers/odoo,microcom/odoo,storm-computers/odoo,hip-odoo/odoo,ygol/odoo,sysadminmatmoz/OCB,laslabs/odoo,hip-odoo/odoo,laslabs/odoo,dfang/odoo,bplancher/odoo,stephen144/odoo,microcom/odoo,optima-ict/odoo,laslabs/odoo,sysadminmatmoz/OCB,sysadminmatmoz/OCB,sysadminmatmoz/OCB,stephen144/odoo,storm-computers/odoo,hip-odoo/odoo,Elico-Corp/odoo_OCB,Elico-Corp/odoo_OCB,Elico-Corp/odoo_OCB,Elico-Corp/odoo_OCB,bplancher/odoo,laslabs/odoo,ygol/odoo,stephen144/odoo,stephen144/odoo,sysadminmatmoz/OCB,ygol/odoo,bplancher/odoo,sysadminmatmoz/OCB,microcom/odoo,optima-ict/odoo,stephen144/odoo,hip-odoo/odoo,storm-computers/odoo,Elico-Corp/odoo_OCB,ygol/odoo,bplancher/odoo,laslabs/odoo,hip-odoo/odoo