### Godot version

Godot Engine v4.0.stable.official.92bee43ad

### System information

Windows 10

### Issue description

The documentation states that passing ```null``` into the image parameter of ```set_custom_mouse_cursor``` will change it back to the system cursor, however I find that it removes the cursor's image entirely, rather than setting it to the system's cursor.


### Steps to reproduce

```var isimage = false
var theimage = load("res://final.png")

func _on_my_button_pressed():
    if isimage == false:
        Input.set_custom_mouse_cursor(theimage, Input.CURSOR_ARROW, Vector2(16,16))
        isimage = true
        
    else:
        Input.set_custom_mouse_cursor(null)
        isimage = false```

When the button is pressed, the cursor is meant to change to the new cursor. When it has been pressed a second time, it changes back to the default cursor. However, upon pressing it a second time, it simply disappears. The cursor becomes visible again when the cursor exits and re-enters the window.

### Minimal reproduction project

[null mouse.zip](https://github.com/godotengine/godot/files/10901969/null.mouse.zip)

SetPriorityClass(GetCurrentProcess(), ABOVE_NORMAL_PRIORITY_CLASS);
		DWORD index = 0;
		HANDLE handle = AvSetMmThreadCharacteristicsW(L"Games", &index);
		if (handle) {
			AvSetMmThreadPriority(handle, AVRT_PRIORITY_CRITICAL);
		}
		
		
		SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_TIME_CRITICAL);
	}
	cursor_shape = CURSOR_ARROW;
	_update_real_mouse_position(MAIN_WINDOW_ID);
	r_error = OK;
	static_cast<OS_Windows *>(OS::get_singleton())->set_main_window(windows[MAIN_WINDOW_ID].hWnd);
	Input::get_singleton()->set_event_dispatch_function(_dispatch_input_events);
}
Vector<String> DisplayServerWindows::get_rendering_drivers_func() {
	Vector<String> drivers;
#ifdef VULKAN_ENABLED
	drivers.push_back("vulkan");
#endif
#ifdef GLES3_ENABLED
	drivers.push_back("opengl3");
#endif
	return drivers;
}
DisplayServer *DisplayServerWindows::create_func(const String &p_rendering_driver, WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Vector2i *p_position, const Vector2i &p_resolution, int p_screen, Error &r_error) {