### Godot version

4.0.dev (f581f21dd61a8fb581b80d07755cdf60c95d146d)

### System information

Windows 10 - Ryzen 7 - 4070ti

### Issue description

When using the threaded resource loader, textures on materials are lost.

This is the scene being loaded in the IDE:
![image](https://github.com/godotengine/godot/assets/1945449/232dd16b-81c4-49cf-a980-3efcfa97ff79)

This is the result in runtime:
![image](https://github.com/godotengine/godot/assets/1945449/235176d3-6058-4bed-8fbe-cad14a5e0d32)


### Steps to reproduce

Use code such as the following to load a scene:
```
func _load_scene(p_scene_path):
	var new_scene : PackedScene
	if ResourceLoader.has_cached(p_scene_path):
		# Load cached scene
		new_scene = ResourceLoader.load(p_scene_path)
	else:
		# Start the loading in a thread
		ResourceLoader.load_threaded_request(p_scene_path)

		# Loop waiting for the scene to load
		while true:
			var progress := []
			var res := ResourceLoader.load_threaded_get_status(p_scene_path, progress)
			if res != ResourceLoader.THREAD_LOAD_IN_PROGRESS:
				break;

			_progress_bar = progress[0]
			await get_tree().create_timer(0.1).timeout

		# Get the loaded scene
		new_scene = ResourceLoader.load_threaded_get(p_scene_path)
	
	$CanvasLayer.visible = false
	add_child(new_scene.instantiate())
```

Now create a scene to load that has a material with a texture.

### Minimal reproduction project

[TestResourceLoader.zip](https://github.com/godotengine/godot/files/11549692/TestResourceLoader.zip)

code += "	vec2 base_uv2 = UV2;\n";
	}
	if (features[FEATURE_HEIGHT_MAPPING] && flags[FLAG_UV1_USE_TRIPLANAR]) {
		
		
		
		if (textures[TEXTURE_ALBEDO].is_valid()) {
			WARN_PRINT(vformat("%s (albedo %s): Height mapping is not supported on triplanar materials. Ignoring height mapping in favor of triplanar mapping.", get_path(), textures[TEXTURE_ALBEDO]->get_path()));
		} else if (!get_path().is_empty()) {
			WARN_PRINT(vformat("%s: Height mapping is not supported on triplanar materials. Ignoring height mapping in favor of triplanar mapping.", get_path()));
		} else {
			
			WARN_PRINT("Height mapping is not supported on triplanar materials. Ignoring height mapping in favor of triplanar mapping.");
		}
	}
	if (!RenderingServer::get_singleton()->is_low_end() && features[FEATURE_HEIGHT_MAPPING] && !flags[FLAG_UV1_USE_TRIPLANAR]) { 
		code += "	{\n";
		code += "		vec3 view_dir = normalize(normalize(-VERTEX)*mat3(TANGENT*heightmap_flip.x,-BINORMAL*heightmap_flip.y,NORMAL));\n"; 
		if (deep_parallax) {
			code += "		float num_layers = mix(float(heightmap_max_layers),float(heightmap_min_layers), abs(dot(vec3(0.0, 0.0, 1.0), view_dir)));\n";
			code += "		float layer_depth = 1.0 / num_layers;\n";
			code += "		float current_layer_depth = 0.0;\n";
			
			code += "		vec2 P = view_dir.xy * heightmap_scale * 0.01;\n";
			code += "		vec2 delta = P / num_layers;\n";
			code += "		vec2 ofs = base_uv;\n";
			if (flags[FLAG_INVERT_HEIGHTMAP]) {
				code += "		float depth = texture(texture_heightmap, ofs).r;\n";
			} else {
				code += "		float depth = 1.0 - texture(texture_heightmap, ofs).r;\n";