### 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)

_THREAD_SAFE_METHOD_
	ERR_FAIL_COND(!windows.has(p_window));
	WindowData &wd = windows[p_window];
	if (wd.fullscreen || wd.maximized) {
		return;
	}
	Point2i offset = _get_screens_origin();
	RECT rc;
	rc.left = p_position.x + offset.x;
	rc.right = p_position.x + wd.width + offset.x;
	rc.bottom = p_position.y + wd.height + offset.y;
	rc.top = p_position.y + offset.y;
	const DWORD style = GetWindowLongPtr(wd.hWnd, GWL_STYLE);
	const DWORD exStyle = GetWindowLongPtr(wd.hWnd, GWL_EXSTYLE);
	AdjustWindowRectEx(&rc, style, false, exStyle);
	MoveWindow(wd.hWnd, rc.left, rc.top, rc.right - rc.left, rc.bottom - rc.top, TRUE);
	wd.last_pos = p_position;
	_update_real_mouse_position(p_window);
}
void DisplayServerWindows::window_set_exclusive(WindowID p_window, bool p_exclusive) {