Fixup order-by test failure

The previous commit fixed a bug when there is no order by, but there
is a remapping. The corresponding change to the
add-dimmension-projections-test didn't happen. This fixes that test failure.

test/metabase/query_processor/middleware/add_dimension_projections_test.clj

@@ -107,7 +107,7 @@
 
 (def ^:private example-query
   {:query
-   {:order-by []
+   {:order-by nil
     :fields
     (mapv #(merge field-defaults %)
           [{:description "A unique internal identifier for the review. Should not be used externally.",