Rename external field reference

https://aip.dev/122#fields-representing-another-resource

Also reorder file to satisfy https://aip.dev/191#file-layout

BUG=chromium:1063474
TEST=./generate.sh

Change-Id: I463b9e7c5e0daa969fb02c7cca4ac51ff1ead3af
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2111114
Commit-Queue: Prathmesh Prabhu <pprabhu@chromium.org>
Tested-by: Prathmesh Prabhu <pprabhu@chromium.org>
Reviewed-by: Alex Zamorzaev <zamorzaev@chromium.org>
2 files changed