Recreate golden file loader for the time limit consistency tests, after
last one was reverted.

This time, a separated test binary is used to avoid dependency clashes
between protobuf libs.

Bug: 935711
Change-Id: I0789418f3a2c6c959845a1926f21832dcd0c389d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1515206
Commit-Queue: G. Silva <gfaus@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Henrique Grandinetti <hgrandinetti@chromium.org>
Cr-Commit-Position: refs/heads/master@{#641039}