### Godot version

4.1

### System information

Godot v4.1.1.stable.mono - Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 2070 SUPER (NVIDIA; 31.0.15.2802) - AMD Ryzen 9 3900X 12-Core Processor (24 Threads)

### Issue description

Saving a MeshInstance3D with a mesh resource imported from a blender file will lose the reference to the mesh resource when reopening de project.

When testing I have found that the uid referencing the mesh saved in the .tscn is the same as the one int the .blend.import and not an unique one for the specific mesh
uid in .tscn: ![image](https://github.com/godotengine/godot/assets/6534007/19458a77-e4a8-4075-b641-d71c043dfca3)
uid in .blend.import: ![image](https://github.com/godotengine/godot/assets/6534007/4208e451-c308-4845-81d4-a45bed8a3169)
I don't know if that is the cause of the error but I have found a way to force it to generate a unique uid:

1. select the mesh in the MeshInstance3D and "Make Unique"
2. reassign the mesh resource to the MeshInstance3D

now the .tscn has a unique uid for the mesh and remains referenced when reopening the project (this happens randomly sometimes too when working on the scene)
![image](https://github.com/godotengine/godot/assets/6534007/3e58b449-4e85-4f1f-9e62-2bd3c62f98ff)




Related: [ #57053](https://github.com/godotengine/godot/issues/57053)



### Steps to reproduce

1. import a .blend file with a mesh (if the .blend has multiple mesh the error doesn't seems reproduce)
2. open the blender importer, set mesh paths and reimport
3. create a new MeshInstance3D node and assign the created .res as a mesh resource
4. save the scene and restart Godot.

### Minimal reproduction project

[mesh_test.zip](https://github.com/godotengine/godot/files/12232647/mesh_test.zip)

config->get_section_keys("params", &sk);
			for (const String &param : sk) {
				Variant value = config->get_value("params", param);
				
				source_file_options[p_files[i]][param] = value;
			}
		}
		base_paths[p_files[i]] = ResourceFormatImporter::get_singleton()->get_import_base_path(p_files[i]);
	}
	if (importer_name == "keep") {
		return OK; 
	}
	ERR_FAIL_COND_V(importer_name.is_empty(), ERR_UNCONFIGURED);
	Ref<ResourceImporter> importer = ResourceFormatImporter::get_singleton()->get_importer_by_name(importer_name);
	Error err = importer->import_group_file(p_group_file, source_file_options, base_paths);
	
	for (const KeyValue<String, HashMap<StringName, Variant>> &E : source_file_options) {
		const String &file = E.key;
		String base_path = ResourceFormatImporter::get_singleton()->get_import_base_path(file);
		Vector<String> dest_paths;
		ResourceUID::ID uid = uids[file];
		{
			Ref<FileAccess> f = FileAccess::open(file + ".import", FileAccess::WRITE);
			ERR_FAIL_COND_V_MSG(f.is_null(), ERR_FILE_CANT_OPEN, "Cannot open import file '" + file + ".import'.");
			
			f->store_line("[remap]");
			f->store_line("");
			f->store_line("importer=\"" + importer->get_importer_name() + "\"");
			int version = importer->get_format_version();
			if (version > 0) {