tests: Remove extra $CMD_PREFIX from test-auto-summary.sh
tests: Remove extra $CMD_PREFIX from test-auto-summary.sh

$OSTREE already has $CMD_PREFIX in it, so adding it again causes you to
call env twice with LD_PRELOAD.

Closes: #372
Approved by: cgwalters

GNOME/ostree,GNOME/ostree,gatispaeglis/ostree,gatispaeglis/ostree,gatispaeglis/ostree,GNOME/ostree,gatispaeglis/ostree,gatispaeglis/ostree,GNOME/ostree,gatispaeglis/ostree,GNOME/ostree