bug#53541: [installer] backtrace during fresh Guix System install after during formatting

[Mathieu Othacehe]

> Fixes: <https://issues.guix.gnu.org/53541>.
>
> * gnu/installer/parted.scm (read-partition-uuid/retry): New procedure.
> (check-user-partitions): Use it.

Pushed as ab974ed709976d34917c8f6f9e5cc0004547af45.

Mathieu