update_chroot: delete --useoldpkg-atoms=dev-lang/go

So that the change (CL:615754) to the toolchain package dev-lang/go will
be picked up.

BUG=b:64542183
TEST=trybot

Change-Id: I9c0db8a6f9c8a3c69694afe4b5122044e8c6cf5c
Reviewed-on: https://chromium-review.googlesource.com/634220
Trybot-Ready: Ke Wu <mikewu@google.com>
Reviewed-by: Rahul Chaudhry <rahulchaudhry@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Ke Wu <mikewu@google.com>
Tested-by: Ke Wu <mikewu@google.com>
1 file changed