update_chroot: move chroot version hooks to chromite BUG=b:298249751 TEST=CQ passes Cq-Depend: chromium:4835160 Change-Id: I35a77199c7c1d1c1021192368e2533d9aa858fa1 Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/4835119 Tested-by: Mike Frysinger <vapier@chromium.org> Reviewed-by: Tim Bain <tbain@google.com> Commit-Queue: Mike Frysinger <vapier@chromium.org>