auto_update: Improve error message when `rsync` was not found (#39791)

Reworded the error message when the `rsync` utility could not be found.

Release Notes:

- N/A
65a38a27a9warrenjokinen committed on 10/10/2025, 9:44:32 PM· committed by GitHubparentd6becab
1 file changedLine totals unavailable