[CP] Do not record alter system change tenant event in __all_server_event_history

src/sql/executor/ob_cmd_executor.cpp

@@ -620,6 +620,7 @@ int ObCmdExecutor::execute(ObExecContext& ctx, ObICmd& cmd)
     }
     case stmt::T_CHANGE_TENANT: {
       DEFINE_EXECUTE_CMD(ObChangeTenantStmt, ObChangeTenantExecutor);
+      sql_text = ObString::make_empty_string();  // do not record
       break;
     }
     case stmt::T_CREATE_FUNC: {