### 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)

}
							}
							values++;
						}
						if (XIMaskIsSet(raw_event->valuators.mask, VALUATOR_TILTY)) {
							HashMap<int, Vector2>::Iterator pen_tilt_y = xi.pen_tilt_y_range.find(device_id);
							if (pen_tilt_y) {
								Vector2 pen_tilt_y_range = pen_tilt_y->value;
								if (pen_tilt_y_range[0] != 0 && *values < 0) {
									xi.tilt.y = *values / -pen_tilt_y_range[0];
								} else if (pen_tilt_y_range[1] != 0) {
									xi.tilt.y = *values / pen_tilt_y_range[1];
								}
							}
							values++;
						}
						HashMap<int, bool>::Iterator pen_inverted = xi.pen_inverted_devices.find(device_id);
						if (pen_inverted) {
							xi.pen_inverted = pen_inverted->value;
						}
						
						
						if (raw_event->time == xi.last_relative_time && rel_x == xi.relative_motion.x && rel_y == xi.relative_motion.y) {
							break; 
						}
						xi.old_raw_pos.x = xi.raw_pos.x;
						xi.old_raw_pos.y = xi.raw_pos.y;
						xi.raw_pos.x = rel_x;
						xi.raw_pos.y = rel_y;
						HashMap<int, Vector2>::Iterator abs_info = xi.absolute_devices.find(device_id);