metadata/OWNERS: Update bot owner

Update bot owner to shared bot owner.

BUG=b:234472251
TEST=None

Cq-Depend: chrome-internal:4796426
Change-Id: I523eb3464a1ba20fcfcbfb4f0758cade93ce446d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/3923626
Tested-by: Alex Klein <saklein@chromium.org>
Auto-Submit: Alex Klein <saklein@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
1 file changed