quick-provision: Await reboot before doing post check.

Quick provisioning path was erroneously expecting PostCheckCrOSUpdate
to await for reboot, while in the non-quick provisioning cases this was
being done prior to that call.  This resulted in some race conditions
and a few attempts to work around it incorrectly.  Now, quick
provisioning can just call AwaitReboot which will ensure that the DUT
has rebooted before doing any other provisioning.

BUG=chromium:812949
TEST=autotest/contrib/loadtest.py
CQ-DEPEND=932362

Change-Id: I93e680d92c8fb7e99008dc3783c10b7af620707a
Reviewed-on: https://chromium-review.googlesource.com/931937
Commit-Ready: David Riley <davidriley@chromium.org>
Tested-by: David Riley <davidriley@chromium.org>
Reviewed-by: Xixuan Wu <xixuan@chromium.org>
1 file changed