[FIX] product: product category smart button: sub categ too
[FIX] product: product category smart button: sub categ too

Before this commit, the smart button on the form of product category
only displayed the number of product for the current category,
whereas the list view of products (when you clicked on the smart button)
displayed all sub-categories products.

After this commit, the behavior is harmonized: all sub-categories products
should be accounted for and displayed

OPW 782905

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo