[Dy2St]Fix re-defined var from merge conflict with two PR (#50597)

paddle/fluid/eager/to_static/run_program_op_func.h

@@ -113,10 +113,6 @@ inline void run_program_ad_func(
     grad_node->SetGradOutMeta(params, /*slot id*/ 1);
 
     VLOG(2) << "clear_no_grad_edges.";
-    auto* forward_global_block = PADDLE_GET_CONST(
-        paddle::framework::BlockDesc*, attrs.at("forward_global_block"));
-    auto* backward_global_block = PADDLE_GET_CONST(
-        paddle::framework::BlockDesc*, attrs.at("backward_global_block"));
     clear_no_grad_edges_with_partial_block(params,
                                            forward_global_block,
                                            backward_global_block,