fix lod_tensor_array gc (#42377)

paddle/fluid/framework/executor_gc_helper.cc

@@ -156,6 +156,9 @@ void DeleteUnusedTensors(const Scope &scope,
       for (auto &t : *lod_tensor_arr) {
         garbages.emplace_back(t.MoveMemoryHolder());
       }
+      // NOTE(wangxi): need clear the vector, otherwise lod_tensor_arr.size() is
+      // wrong, if size() decrease in next step, an error maybe occur.
+      lod_tensor_arr->clear();
     } else if (var->IsType<Strings>()) {
     } else {
       PADDLE_THROW(platform::errors::Unimplemented(