Revert "Switch Nova to use oslo.concurrency"

This patch made unit tests stop running (always runs 0 unit tests) we
should revert and put a check in place to prevent that from happening
so that we don't regress the rest of Nova trying to figure out the
oslo.concurrency issue.

This reverts commit 382294762b.

Change-Id: I98b04ac2a0ba67ba8af44867799317fdf95b8aff

tools/pretty_tox.sh

@@ -3,4 +3,4 @@
 set -o pipefail
 
 TESTRARGS=$1
-python -m oslo.concurrency.lockutils python setup.py testr --slowest --testr-args="--subunit $TESTRARGS" | $(dirname $0)/subunit-trace.py -f
+python -m nova.openstack.common.lockutils python setup.py testr --slowest --testr-args="--subunit $TESTRARGS" | $(dirname $0)/subunit-trace.py -f