Fix Settings backup and restore, reports "no backup found" when they …

[jefflord]

…do exist. #21869

Summary of the Pull Request

If you delete all the files in the temp backup locations (e.g. "C:\Users\XXX\AppData\Local\Temp\PowerToys_settings_133123828902788367"), but leave the folder there, empty, you will get this error.

PR Checklist

• [X] Closes: #21869
• [ ] Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• [ ] Tests: Added/updated and all pass
• [ ] Localization: All end user facing strings can be localized
• [ ] Dev docs: Added/updated
• [ ] New binaries: Added on the required places
  • [ ] JSON for signing for new binaries
  • [ ] WXS for installer for new binaries and localization folder
  • [ ] YML for CI pipeline for new test projects
  • [ ] YML for signed pipeline
• [ ] Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

[jefflord]

@niels9001, @stefansjfw just wanted to point this one out. I think it rather "serious" for backup/restore, but also has a pretty simple and safe fix.