### 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)

if (SUCCEEDED(hr) && (x > 0) && (y > 0)) {
			dpiX = (int)x;
			dpiY = (int)y;
		}
	} else {
		static int overallX = 0, overallY = 0;
		if (overallX <= 0 || overallY <= 0) {
			HDC hdc = GetDC(nullptr);
			if (hdc) {
				overallX = GetDeviceCaps(hdc, LOGPIXELSX);
				overallY = GetDeviceCaps(hdc, LOGPIXELSY);
				ReleaseDC(nullptr, hdc);
			}
		}
		if (overallX > 0 && overallY > 0) {
			dpiX = overallX;
			dpiY = overallY;
		}
	}
	return (dpiX + dpiY) / 2;
}
static BOOL CALLBACK _MonitorEnumProcDpi(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData) {
	EnumDpiData *data = (EnumDpiData *)dwData;
	if (data->count == data->screen) {
		data->dpi = QueryDpiForMonitor(hMonitor);
	}
	data->count++;
	return TRUE;
}
int DisplayServerWindows::screen_get_dpi(int p_screen) const {