Fix 10.3.6 default schema user name

Author: CarolynRountree

core/src/main/python/wlsdeploy/util/weblogic_helper.py

@@ -114,7 +114,9 @@ def get_stb_user_name(self, rcu_prefix):
         :param rcu_prefix: the RCU prefix
         :return: the Service Table schema user name
         """
-        return rcu_prefix + '_STB'
+        if self.is_weblogic_version_or_above('12.1.2'):
+            return rcu_prefix + '_STB'
+        return rcu_prefix + '_MDS'
 
     def get_jrf_service_table_datasource_name(self):
         """