[FIX] point_of_sale: Variant description doesn't show on POS invoice

The display_name of the product  must be shown as the name of the invoice line
to have the same behavior as in Sale app.

opw:771302

addons/point_of_sale/models/pos_order.py

@@ -193,7 +193,7 @@ class PosOrder(models.Model):
         # We convert a new id object back to a dictionary to write to
         # bridge between old and new api
         inv_line = invoice_line._convert_to_write({name: invoice_line[name] for name in invoice_line._cache})
-        inv_line.update(price_unit=line.price_unit, discount=line.discount)
+        inv_line.update(price_unit=line.price_unit, discount=line.discount, name=inv_name)
         return InvoiceLine.sudo().create(inv_line)
 
     def _create_account_move_line(self, session=None, move=None):