[autotest] Set TestBed.job

Adds the same magic that assigns Host.job to TestBed.

BUG=chromium:584541
TEST=modified testbed_DummyTest to hit afe_utils.host_in_lab then ran:
./test_droid.py emulator-5554,92c52320 testbed_DummyTest

Change-Id: I7aeccac7e0995fa60d3c66f0ae0fc5cee0bd2df5
Reviewed-on: https://chromium-review.googlesource.com/326200
Commit-Ready: Simran Basi <sbasi@chromium.org>
Tested-by: Simran Basi <sbasi@chromium.org>
Reviewed-by: Dan Shi <dshi@chromium.org>
Reviewed-by: Kris Rambish <krisr@chromium.org>
2 files changed