[FIX] website_sale: keep "sorting by" on searching by attributes

Searching by attributes works via a separate form. It has a copy of other search
parameters (`category`, `search`), but not `order`.

STEPS

1) enable View "Products Attribute's Filters" in eCommerce
2) enable View "Show Sort by" in eCommerce
3) Set sorting to specific value
4) Change Product Filters Attribute values
5) as you can see, the sorting set in Pt3 is lost....

opw-2956280

closes odoo/odoo#98553

Signed-off-by: William Braeckman (wbr) <wbr@odoo.com>