Migrate internal linux & CrOS builders' tests to bionic.

Includes: linux-chrome, linux-chromeos-chrome,
lacros-amd64-generic-chrome, and chromeos-betty-pi-arc.

crrev.com/i/3830003 allocates the machines for this.

Bug: 1208582
Change-Id: I028f70154e1bd6a4ef09c3a534fe75623225dcef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2892172
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
Cr-Commit-Position: refs/heads/master@{#882648}
NOKEYCHECK=True
GitOrigin-RevId: 11f752f4f43abdbd5e51e26f7b6eaa2798e0b104
4 files changed