Delete stale descpb.bin

The generation of this file was disabled in crosreview.com/2075163 but
another in-flight CL crosreview.com/2099564 reintroduced it.

This file hasn't been updated since, and is stale.
+ Add gitignore to avoid future commits of this file (if someone uses
  really old version of the generation script.

BUG=None
TEST=./generate.sh

Change-Id: Ice5e0bd0416bc95695227203337be2e8ed780eef
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2149708
Tested-by: Prathmesh Prabhu <pprabhu@chromium.org>
Auto-Submit: Prathmesh Prabhu <pprabhu@chromium.org>
Reviewed-by: Sean Abraham <seanabraham@chromium.org>
Commit-Queue: Sean Abraham <seanabraham@chromium.org>
3 files changed