go.mod: update proto dep; stop using now-deleted fields in code

I removed two fields from the infra/proto message this afternoon, so
they'll never be set. They can be safely removed.

Bug: 1130018
Change-Id: Ie3a34def8178556004f92926c1f0cac346b7ccb5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/go/+/2422670
Reviewed-by: Navil Perez <navil@google.com>
Commit-Queue: Navil Perez <navil@google.com>
Tested-by: Navil Perez <navil@google.com>
Auto-Submit: Sean Abraham <seanabraham@chromium.org>
3 files changed