Remove order by sku from variant scope

This "fixes" the variant scope issue but I'm not sure it's the solution
we want. I suppose it depends if ordering by sku is important here.

Co-authored-by: An Stewart <andrew@super.gd>
(cherry picked from commit c4bd75a)

backend/app/controllers/spree/admin/stock_items_controller.rb

@@ -56,7 +56,7 @@ def load_stock_management_data
       def variant_scope
         scope = Spree::Variant
           .accessible_by(current_ability)
-          .distinct.order(:sku)
+          .distinct
           .includes(
             :images,
             stock_items: :stock_location,