### 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)

}
#define MI_WP_SIGNATURE 0xFF515700
#define SIGNATURE_MASK 0xFFFFFF00
#define IsPenEvent(dw) (((dw)&SIGNATURE_MASK) == MI_WP_SIGNATURE)
#define IsTouchEvent(dw) (IsPenEvent(dw) && ((dw)&0x80))
void DisplayServerWindows::_touch_event(WindowID p_window, bool p_pressed, float p_x, float p_y, int idx) {
	if (touch_state.has(idx) == p_pressed) {
		return;
	}
	if (p_pressed) {
		touch_state.insert(idx, Vector2(p_x, p_y));
	} else {
		touch_state.erase(idx);
	}
	Ref<InputEventScreenTouch> event;
	event.instantiate();
	event->set_index(idx);
	event->set_window_id(p_window);
	event->set_pressed(p_pressed);
	event->set_position(Vector2(p_x, p_y));
	Input::get_singleton()->parse_input_event(event);
}
void DisplayServerWindows::_drag_event(WindowID p_window, float p_x, float p_y, int idx) {