[autotest] Use a RetryingAFE in gs_offloader.

Sometimes the AFE gives 500 errors to gs_offloader, so we want to
do our best to ignore them.

BUG=chromium:364327
TEST=unit tests
DEPLOY=gs_offloader

Change-Id: I37522bcb32d57df20c0dad6356e0306266d3b62b
Reviewed-on: https://chromium-review.googlesource.com/216353
Commit-Queue: Richard Barnette <jrbarnette@chromium.org>
Tested-by: Richard Barnette <jrbarnette@chromium.org>
Reviewed-by: Prashanth B <beeps@chromium.org>
1 file changed