autotest: Remove unnecessary firewall wrangling for stumpy cells

The latest stumpy images for stumpy cells no longer require holes
to be punched in the firewall because the firewall is effectively
disabled at startup time.

BUG=chromium:241617
TEST=This broke my cell, I updated the image, and then tests worked
again.

Change-Id: Ie76a26c7a6d27db64e8d197e9f4e05d97a8aac74
Reviewed-on: https://gerrit.chromium.org/gerrit/57526
Tested-by: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Commit-Queue: Christopher Wiley <wiley@chromium.org>
1 file changed