update ad abtest threshold 198/ab8,9: mean/18*7 -> mean/36*13

config.py

@@ -933,8 +933,8 @@ class BaseConfig(object):
             'ab5': {'group': 1 / 2, 'mean_group': 1 / 2},
             'ab6': {'group': 7 / 18, 'mean_group': 7 / 18},
             'ab7': {'group': 7 / 18, 'mean_group': 7 / 18},
-            'ab8': {'group': 7 / 18, 'mean_group': 7 / 18},
-            'ab9': {'group': 7 / 18, 'mean_group': 7 / 18},
+            'ab8': {'group': 13 / 36, 'mean_group': 13 / 36},
+            'ab9': {'group': 13 / 36, 'mean_group': 13 / 36},
         }
     }