Deleting Obsolete Icon References from icons.screen0.yaml

Issue Description

~/.config/xfce4/desktop/icons.screen0.yaml

This file appears to keep position data for desktop files even after those files have been removed. This clutters up the yaml file and can potentially cause conflicts by listing multiple icons in the same location.

Steps to Reproduce Issue

1. Add a file to the desktop. The yaml file should automatically update with the position data for this file.
2. Remove the file from the desktop.
3. The reference to the file remains in the yaml.

Expected Behavior

I would expect the yaml file to reflect only those icons currently on the desktop, meaning anything removed from the desktop should also be removed from this file.

Environment & Versions

I'm on Xubuntu 25.04, xfdesktop version 4.20.1, running on Xfce 4.20 with X11 and Thunar 4.20.2.