Remove prototype for project configs

This has since been launched under src/config and the prototype is not
obsolete.

Change-Id: I33d09b6b28bcaf77106b52d469aaa3f562141bc1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2349955
Tested-by: C Shapiro <shapiroc@chromium.org>
Auto-Submit: C Shapiro <shapiroc@chromium.org>
Reviewed-by: David Burger <dburger@chromium.org>
Commit-Queue: David Burger <dburger@chromium.org>
24 files changed