### 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)

DisplayServer *ds = memnew(DisplayServerWindows(p_rendering_driver, p_mode, p_vsync_mode, p_flags, p_position, p_resolution, p_screen, r_error));
	if (r_error != OK) {
		if (p_rendering_driver == "vulkan") {
			String executable_name = OS::get_singleton()->get_executable_path().get_file();
			OS::get_singleton()->alert(
					vformat("Your video card drivers seem not to support the required Vulkan version.\n\n"
							"If possible, consider updating your video card drivers or using the OpenGL 3 driver.\n\n"
							"You can enable the OpenGL 3 driver by starting the engine from the\n"
							"command line with the command:\n\n    \"%s\" --rendering-driver opengl3\n\n"
							"If you have recently updated your video card drivers, try rebooting.",
							executable_name),
					"Unable to initialize Vulkan video driver");
		} else {
			OS::get_singleton()->alert(
					"Your video card drivers seem not to support the required OpenGL 3.3 version.\n\n"
					"If possible, consider updating your video card drivers.\n\n"
					"If you have recently updated your video card drivers, try rebooting.",
					"Unable to initialize OpenGL video driver");
		}
	}
	return ds;
}
void DisplayServerWindows::register_windows_driver() {