Fix yml test

Author: przemekwitek

x-pack/plugin/src/test/resources/rest-api-spec/test/ml/data_frame_analytics_crud.yml

@@ -1810,7 +1810,7 @@ setup:
       "maximum_number_trees": 400,
       "feature_bag_fraction": 0.3,
       "training_percent": 60.3,
-      "num_top_classes": 0
+      "num_top_classes": 2
     }
   }}
   - is_true: create_time