[VitisAI] update graph_save (microsoft#20979)

### Description
<!-- Describe your changes. -->
Fix the threshold limit


### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
We use this to debug the graph after each graph transformation. But, the
const data inside the model is useless.
So, we decided to remove that information to save disk space.

Co-authored-by: Chunye Wang <[email protected]>

onnxruntime/core/providers/vitisai/imp/graph.cc

@@ -103,15 +103,18 @@ void graph_remove_node(Graph& graph, const NodeInput& node_input) {
 }
 
 void graph_save(const Graph& graph, const std::string& filename, const std::string& filename_dat, size_t initializer_size_threshold) {
-  auto& model = const_cast<Model&>(graph.GetModel());
-  std::unique_ptr<ONNX_NAMESPACE::ModelProto> model_proto;
-
+  auto model_proto = const_cast<onnxruntime::Model&>(graph.GetModel()).ToProto();
+  auto graph_proto_subgraph = graph.ToGraphProto();
+  *model_proto->mutable_graph() = *graph_proto_subgraph;
+  auto& logger = logging::LoggingManager::DefaultLogger();
+  auto filename_data_relative_path = std::filesystem::path();
+  auto model = Model::Create(std::move(*model_proto), ToPathString(filename), nullptr, logger);
   if (initializer_size_threshold == std::numeric_limits<size_t>::max()) {
-    model_proto = model.ToProto();
+    model_proto = model->ToProto();
   } else {
-    model_proto = model.ToGraphProtoWithExternalInitializers(filename_dat, graph.ModelPath().ToPathString(), initializer_size_threshold);
+    model_proto = model->ToGraphProtoWithExternalInitializers(filename_dat, ToPathString(filename), initializer_size_threshold);
   }
-  auto& metadata = model.MetaData();
+  auto& metadata = model->MetaData();
   if (!metadata.empty()) {
     auto metadata_props = model_proto->mutable_metadata_props();
     metadata_props->Clear();
@@ -121,18 +124,6 @@ void graph_save(const Graph& graph, const std::string& filename, const std::stri
       *prop->mutable_value() = m.second;
     }
   }
-  // use relative path as data storage.
-  auto graph_proto = model_proto->mutable_graph();
-  *graph_proto = *graph.ToGraphProto();
-  for (int i = 0; i < graph_proto->mutable_initializer()->size(); i++) {
-    auto mutable_external_data = graph_proto->mutable_initializer()->at(i).mutable_external_data();
-    for (int j = 0; j < mutable_external_data->size(); j++) {
-      auto& external_data = mutable_external_data->at(j);
-      if (*external_data.mutable_key() == "location")
-        *external_data.mutable_value() = std::filesystem::path(*external_data.mutable_value()).filename().u8string();
-    }
-  }
-
   std::fstream output(filename, std::ios::out | std::ios::trunc | std::ios::binary);
   bool result = model_proto->SerializeToOstream(output);
   output << std::flush;