Fix duplicate uid/gid for arcvm-boot-notification-server

Uid/gid arcvm-boot-notification-server currently conflicts with another
user. Update to use a free uid/gid number.

BUG=b:155445534
TEST=profiles/base/accounts/display-accts.py --lint

Change-Id: Ia4859528c828f9a07bbb03d6e63c35ae3335edfa
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/eclass-overlay/+/2216490
Auto-Submit: Willie Koomson <wvk@google.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Willie Koomson <wvk@google.com>
Tested-by: Willie Koomson <wvk@google.com>