GuestOS: Update OWNERS

Updating OWNERS file to reflect recent team changes

BUG=b:328241008
TEST=None

Change-Id: Idb8032a7e43e485c10542c87005f854a6f615912
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5345752


Reviewed-by: David Munro <davidmunro@google.com>
Commit-Queue: Dennis Kempin <denniskempin@google.com>
Reviewed-by: Joel Hockey <joelhockey@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1270375}