revised ballgown

defaults

@@ -17,5 +17,5 @@
     "stringtie_docker": "registry.cn-shanghai.aliyuncs.com/pgx-docker-registry/stringtie:v1.3.4",
     "stringtie_cluster": "OnDemand bcs.a2.large img-ubuntu-vpc",
     "ballgown_docker": "registry.cn-shanghai.aliyuncs.com/pgx-docker-registry/pgx-ballgown:0.0.1",
-    "ballgown_cluster": "OnDemand bcs.b2.large img-ubuntu-vpc"
+    "ballgown_cluster": "OnDemand bcs.a2.large img-ubuntu-vpc"
 }