Set Elasticsearch replica count default to 1. (#7108)

model/config.go

@@ -123,7 +123,7 @@ const (
 	ELASTICSEARCH_SETTINGS_DEFAULT_CONNECTION_URL      = ""
 	ELASTICSEARCH_SETTINGS_DEFAULT_USERNAME            = ""
 	ELASTICSEARCH_SETTINGS_DEFAULT_PASSWORD            = ""
-	ELASTICSEARCH_SETTINGS_DEFAULT_POST_INDEX_REPLICAS = 2
+	ELASTICSEARCH_SETTINGS_DEFAULT_POST_INDEX_REPLICAS = 1
 	ELASTICSEARCH_SETTINGS_DEFAULT_POST_INDEX_SHARDS   = 1
 )