### 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)

return true;
}
void DisplayServerWindows::enable_for_stealing_focus(OS::ProcessID pid) {
	_THREAD_SAFE_METHOD_
	AllowSetForegroundWindow(pid);
}
int DisplayServerWindows::keyboard_get_layout_count() const {
	return GetKeyboardLayoutList(0, nullptr);
}
int DisplayServerWindows::keyboard_get_current_layout() const {
	HKL cur_layout = GetKeyboardLayout(0);
	int layout_count = GetKeyboardLayoutList(0, nullptr);
	HKL *layouts = (HKL *)memalloc(layout_count * sizeof(HKL));
	GetKeyboardLayoutList(layout_count, layouts);
	for (int i = 0; i < layout_count; i++) {
		if (cur_layout == layouts[i]) {
			memfree(layouts);
			return i;
		}
	}
	memfree(layouts);
	return -1;
}
void DisplayServerWindows::keyboard_set_current_layout(int p_index) {