### Godot version

4.0.3.stable

### System information

windows 11

### Issue description

fullscreen on the window node is not working and will show up as a windowed.

### Steps to reproduce

disable Embed Subwindows in Project Settings/Display/Window.
create a window node and set its mode to fullscreen.

### Minimal reproduction project

[fullscreen.zip](https://github.com/godotengine/godot/files/11821834/fullscreen.zip)
DisplayServer::get_singleton()->window_set_rect_changed_callback(callable_mp(this, &Window::_rect_changed_callback), window_id);
	DisplayServer::get_singleton()->window_set_window_event_callback(callable_mp(this, &Window::_event_callback), window_id);
	DisplayServer::get_singleton()->window_set_input_event_callback(callable_mp(this, &Window::_window_input), window_id);
	DisplayServer::get_singleton()->window_set_input_text_callback(callable_mp(this, &Window::_window_input_text), window_id);
	DisplayServer::get_singleton()->window_set_drop_files_callback(callable_mp(this, &Window::_window_drop_files), window_id);
}
Viewport *Window::get_embedder() const {
	ERR_READ_THREAD_GUARD_V(nullptr);
	Viewport *vp = get_parent_viewport();
	while (vp) {
		if (vp->is_embedding_subwindows()) {
			return vp;
		}
		if (vp->get_parent()) {
			vp = vp->get_parent()->get_viewport();
		} else {
			vp = nullptr;
		}
	}
	return nullptr;
}
void Window::_notification(int p_what) {