### 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)
if (embedder) {
					if (initial_position != WINDOW_INITIAL_POSITION_ABSOLUTE) {
						position = (embedder->get_visible_rect().size - size) / 2;
					}
					embedder->_sub_window_register(this);
					RS::get_singleton()->viewport_set_update_mode(get_viewport_rid(), RS::VIEWPORT_UPDATE_WHEN_PARENT_VISIBLE);
					_update_window_size();
				}
			} else {
				if (!get_parent()) {
					
					visible = true; 
					window_id = DisplayServer::MAIN_WINDOW_ID;
					DisplayServer::get_singleton()->window_attach_instance_id(get_instance_id(), window_id);
					_update_from_window();
					
					{
						position = DisplayServer::get_singleton()->window_get_position(window_id);
						size = DisplayServer::get_singleton()->window_get_size(window_id);
						focused = DisplayServer::get_singleton()->window_is_focused(window_id);
					}
					_update_window_size(); 
					_update_viewport_size(); 
					_update_window_callbacks();
					RS::get_singleton()->viewport_set_update_mode(get_viewport_rid(), RS::VIEWPORT_UPDATE_WHEN_VISIBLE);
				} else {
					
					if (visible) {
						_make_window();