[FIX] product: Inventory at Date does not show the correct valuation

Fine tuning of this commit: 51d072db44

When clicking on the group of the Inventory at Date, the
product.price.inventory must follow the same order as the
read_group in stock.history.

opw:747857

addons/product/models/product.py

@@ -562,7 +562,7 @@ class ProductProduct(models.Model):
         history = self.env['product.price.history'].search([
             ('company_id', '=', company_id),
             ('product_id', 'in', self.ids),
-            ('datetime', '<=', date or fields.Datetime.now())], limit=1)
+            ('datetime', '<=', date or fields.Datetime.now())], order='datetime desc,id desc', limit=1)
         return history.cost or 0.0
 
     def _need_procurement(self):