systemd-run runs the detached child as a transient unit with
WorkingDirectory=/, so a relative $0 (e.g. ./uninstall-fleetd-linux.sh
per the uninstall guide) couldn't be found and the removal silently
never ran. Resolve $0 to an absolute path before re-exec.
Fixes#49411
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
- **Bug Fixes**
- Improved the Linux uninstall process so the detached cleanup task
always runs from the correct script location.
- Enhanced compatibility between systemd-based environments and
non-systemd systems.
- Better supports script paths that include spaces or special
characters.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Jake Stenger
f3bc510d2b