Switch hive_enable_db_notification's default value

Make this change for CDH 5.13.0.

And do so, such that the user may...
* easily observe the new default value
* easily override the new default value

Change-Id: Ic2805ee0fb6bc2d96144e86b8a3f49beae3e1cef

sahara/plugins/cdh/cloudera_utils.py

@@ -627,6 +627,9 @@ class ClouderaUtils(object):
         yarn = cm_cluster.get_service(self.YARN_SERVICE_NAME)
         yield yarn.enable_rm_ha(new_rm_host_id=new_rm_host_name)
 
+    def _load_version_specific_instance_configs(self, instance, default_conf):
+        pass
+
     def _get_configs(self, service, cluster=None, instance=None):
         def get_hadoop_dirs(mount_points, suffix):
             return ','.join([x + suffix for x in mount_points])
@@ -823,6 +826,9 @@ class ClouderaUtils(object):
                 }
             }
 
+            self._load_version_specific_instance_configs(
+                instance, instance_default_confs)
+
             ng_user_confs = self.pu.convert_process_configs(
                 instance.node_group.node_configs)
             all_confs = s_cfg.merge_configs(all_confs, ng_user_confs)

sahara/plugins/cdh/v5_13_0/cloudera_utils.py

@@ -26,3 +26,9 @@ class ClouderaUtilsV5130(cu.ClouderaUtils):
         self.pu = pu.PluginUtilsV5130()
         self.validator = validation.ValidatorV5130
         self.c_helper = config_helper.ConfigHelperV5130()
+
+    def _load_version_specific_instance_configs(self, instance, default_conf):
+        if instance.node_group.node_configs.get('HIVEMETASTORE', {}).get(
+                'hive_enable_db_notification', None) is None:
+            default_conf['HIVEMETASTORE']['hive_enable_db_notification'] = (
+                'true')

sahara/plugins/cdh/v5_13_0/resources/hive-hivemetastore.json

@@ -159,7 +159,7 @@
         "desc": "Enable stored notifications of metadata changes. When enabled, each metadata change will be stored in NOTIFICATION_LOG.",
         "display_name": "Enable Stored Notifications in Database",
         "name": "hive_enable_db_notification",
-        "value": "false"
+        "value": "true"
     },
     {
         "desc": "When set, this role's process is automatically (and transparently) restarted in the event of an unexpected failure.",