[-] BO : Fix #PSCFV-10520

`$attribute['id_attribute_group']` [here](https://github.com/PrestaShop/PrestaShop/blob/c2b9ff40ef4fe9d8d7da7e3cb3d9ccf19f2eb594/controllers/admin/AdminProductsController.php#L3648) was NULL in some cases which caused invalid JavaScript.