### 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_
	p_screen = _get_screen_index(p_screen);
	EnumDpiData data = { 0, p_screen, 72 };
	EnumDisplayMonitors(nullptr, nullptr, _MonitorEnumProcDpi, (LPARAM)&data);
	return data.dpi;
}
Color DisplayServerWindows::screen_get_pixel(const Point2i &p_position) const {
	Point2i pos = p_position + _get_screens_origin();
	POINT p;
	p.x = pos.x;
	p.y = pos.y;
	if (win81p_LogicalToPhysicalPointForPerMonitorDPI) {
		win81p_LogicalToPhysicalPointForPerMonitorDPI(0, &p);
	}
	HDC dc = GetDC(0);
	if (dc) {
		COLORREF col = GetPixel(dc, p.x, p.y);
		if (col != CLR_INVALID) {
			ReleaseDC(NULL, dc);
			return Color(float(col & 0x000000FF) / 256.0, float((col & 0x0000FF00) >> 8) / 256.0, float((col & 0x00FF0000) >> 16) / 256.0, 1.0);
		}
		ReleaseDC(NULL, dc);
	}
	return Color();
}
Ref<Image> DisplayServerWindows::screen_get_image(int p_screen) const {