update-ids-ruleset: Set correct ownership for the rulestarball.

The script usualy will be executed by cron which will start it with
root permissions, so the downloaded tarball is owned by this user.

This has to be changed to the user which runs the WUI (nobody:nobody) to
allow, changing the ruleset to an other one and to display the ruleset area.

Fixes #12066

Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>