Fix test_that run for non-telemtry tests.

Do not add the autotest_dir argument to test_that
for non-telemetry tests.
Minor change: Remove a leftover print from download_images
unit test.

BUG: chromium:679001
TEST:crosperf unit tests
Change-Id: I0ff5365902af40097b61ae57d7c0d8d43ea308a8
Reviewed-on: https://chromium-review.googlesource.com/426073


Reviewed-by: Caroline Tice <cmtice@chromium.org>
Commit-Queue: Manoj Gupta <manojgupta@chromium.org>
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Trybot-Ready: Manoj Gupta <manojgupta@chromium.org>