use artifacts_gs_location, update ArtifactsByService

Requiring artifacts_gs_location on every artifact type produces an
explosion in builder_config size.

Fix typo in the (as yet unused) artifact_types field name.

Add the service blocks needed for transitioning legacy artifacts, with
notes on the legacy artifacts, for that step in the migration.

BUG=chromium:1034529
TEST=generate

Change-Id: I9fa97ec5df6147d2eecc781fc38c2427e659b954
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2163165
Tested-by: LaMont Jones <lamontjones@chromium.org>
Reviewed-by: David Burger <dburger@chromium.org>
Commit-Queue: David Burger <dburger@chromium.org>
Auto-Submit: LaMont Jones <lamontjones@chromium.org>
4 files changed