Add direct load retry error code

src/share/ob_ddl_common.h

@@ -297,6 +297,7 @@ static inline bool is_direct_load_retry_err(const int ret)
   return is_ddl_stmt_packet_retry_err(ret) || ret == OB_TABLET_NOT_EXIST || ret == OB_LS_NOT_EXIST
     || ret == OB_NOT_MASTER
     || ret == OB_TASK_EXPIRED
+    || ret == OB_REPLICA_NOT_READABLE
     ;
 }