### 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);
	EnumRefreshRateData data = { 0, p_screen, SCREEN_REFRESH_RATE_FALLBACK };
	EnumDisplayMonitors(nullptr, nullptr, _MonitorEnumProcRefreshRate, (LPARAM)&data);
	return data.rate;
}
void DisplayServerWindows::screen_set_keep_on(bool p_enable) {
	if (keep_screen_on == p_enable) {
		return;
	}
	if (p_enable) {
		const String reason = "Godot Engine running with display/window/energy_saving/keep_screen_on = true";
		Char16String reason_utf16 = reason.utf16();
		REASON_CONTEXT context;
		context.Version = POWER_REQUEST_CONTEXT_VERSION;
		context.Flags = POWER_REQUEST_CONTEXT_SIMPLE_STRING;
		context.Reason.SimpleReasonString = (LPWSTR)(reason_utf16.ptrw());
		power_request = PowerCreateRequest(&context);
		if (power_request == INVALID_HANDLE_VALUE) {
			print_error("Failed to enable screen_keep_on.");