[REF] product_main_seller: Remover campo alias default_supplier_id

- El campo era innecesario, era solo un alias a main_seller_id
- Los addons custom ya usan main_seller_id directamente
- No modificar addons OCA con extensiones que no son necesarias

product_main_seller/models/product_template.py

@@ -18,15 +18,6 @@ class ProductTemplate(models.Model):
         store=True,
     )
 
-    default_supplier_id = fields.Many2one(
-        comodel_name="res.partner",
-        string="Default Supplier",
-        help="The main/default supplier for this product",
-        related="main_seller_id",
-        store=True,
-        readonly=False,
-    )
-
     @api.depends("variant_seller_ids.sequence", "variant_seller_ids.partner_id.active")
     def _compute_main_seller_id(self):
         for template in self: