set Flag_control_flow_use_new_executor=true by default (#49447)

paddle/fluid/framework/new_executor/interpretercore.cc

@@ -45,7 +45,7 @@ PADDLE_DEFINE_EXPORTED_bool(new_executor_use_local_scope,
                             "Use local_scope in new executor(especially used "
                             "in UT), can turn off for better performance");
 PADDLE_DEFINE_EXPORTED_bool(control_flow_use_new_executor,
-                            false,
+                            true,
                             "Use new executor in control flow op");
 
 DECLARE_bool(check_nan_inf);