test: Delete RTD API

This API was moved to chromiumos/config in crosreview.com/2158809

BUG=chromium:1069902
TEST=./generate.sh

Change-Id: Ibb757e3d706da9da87efd782be209af04eec6ef6
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2158908
Tested-by: Prathmesh Prabhu <pprabhu@chromium.org>
Reviewed-by: Alex Zamorzaev <zamorzaev@chromium.org>
Commit-Queue: Prathmesh Prabhu <pprabhu@chromium.org>
4 files changed