[FIX] account_edi{,_facturx}: properly retrieve product/description

Odoo attaches factur-x doc to every invoice pdf. That data can be used to upload
invoice to another Odoo instance.

On uploading such an invoice, Odoo tries to find product in its DB. But it
doesn't work if original product has Sales Description which is by default
copied to line's Description (field `name`).

Fix it by searching by first line in the name value of factur-x. Product name
doesn't contain \n symbol in most cases anyway.

This commit doesn't fix factur-x doc generation because of stable version
policy. In next Odoo release we should use separate factur-x attributes for
product name and invoice line description.

opw-2878530

closes odoo/odoo#95066

Signed-off-by: William André (wan) <wan@odoo.com>