Remove temporary workaround for nightly tests locking.

Due to issues with mobiletc-prebuild not being able to access
the afe locking mechanisms, the nightly tests were temporarily
using the old file locking mechanism.  The issues with the role
account using the afe locks has been resolved, so this CL reverts
the nightly tests to using the afe machine locking mechanism.

BUG=None
TEST=Ran crosperf tests on chrotomation2 from role account using
afe locking mechanism.

Change-Id: I243c28d80718c2e98913ad49d50bf5b46ff82758
Reviewed-on: https://chrome-internal-review.googlesource.com/219905
Reviewed-by: Yunlian Jiang <yunlian@google.com>
Commit-Queue: Caroline Tice <cmtice@google.com>
Tested-by: Caroline Tice <cmtice@google.com>
2 files changed