Bug 470081

SUMMARY
This issue has been happening to me every few months for almost 2 years now and now it finally annoyed me enough to report it.

Every now and then, after a reboot, all my desktop icons are gone, I can't launch any application from plasmashell, and dozens of GB of RAM are being used by it.

When it happens, dmesg shows a lot of out of memory errors and restaring plasmashell has no effect:
```
comm: plasmashell, not enough memory for the allocation
```

To fix this I have no choice but to delete `~/.config/plasma-org.kde.plasma.desktop-appletsrc` and restart plasmashell, which resets all my desktop icons, the widgets, and the taskbar to their defaults, then the issue happens again after a few weeks, sometimes a few months.

I took a look at my  `~/.config/plasma-org.kde.plasma.desktop-appletsrc` file before deleting it and it had a line with almost 2 MILLION characters in the ScreenMapping section, with a really long list of files that have been on my desktop at some point (either directly or in a subdirectory) and aren't there anymore. I can't upload this file for privacy reasons unfortunately.

This issue has happened to me on different distros and KDE versions over the years, not just arch, so it's either me doing something wrong or a plasmashell bug.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux amd64, Kernel 6.3.2
KDE Plasma Version: 5.27.5 from official repos
KDE Frameworks Version: 5.106.0 from official repos
Qt Version: 5.15.9 from official repos
Graphics Platform: X11