pciguard: Fix the uid/gid

Choose the next available UID/GID from
./display-accts.py --show-free

BUG=b:171541662,b:167448768
TEST=display-accts.py --lint

Change-Id: Ibbb7b09076e2c195ef19f9ff077e49750378d7cc
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/eclass-overlay/+/2577410
Reviewed-by: Aashay Shringarpure <aashay@google.com>
Reviewed-by: John Bates <jbates@chromium.org>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Tested-by: Rajat Jain <rajatja@google.com>
Commit-Queue: Rajat Jain <rajatja@google.com>