### 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)

EnumScreenData *data = (EnumScreenData *)dwData;
	if (data->monitor == hMonitor) {
		data->screen = data->count;
	}
	data->count++;
	return TRUE;
}
static BOOL CALLBACK _MonitorEnumProcCount(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData) {
	int *data = (int *)dwData;
	(*data)++;
	return TRUE;
}
int DisplayServerWindows::get_screen_count() const {
	_THREAD_SAFE_METHOD_
	int data = 0;
	EnumDisplayMonitors(nullptr, nullptr, _MonitorEnumProcCount, (LPARAM)&data);
	return data;
}
int DisplayServerWindows::get_primary_screen() const {
	EnumScreenData data = { 0, 0, 0 };
	EnumDisplayMonitors(nullptr, nullptr, _MonitorEnumProcPrim, (LPARAM)&data);
	return data.screen;
}
int DisplayServerWindows::get_keyboard_focus_screen() const {