Delete unused lockfile dependency in test-requirement.txt
Delete unused lockfile dependency in test-requirement.txt

Please refer to
http://lists.openstack.org/pipermail/openstack-dev/2015-September/074818.html

Change-Id: If37f94f8a0879ecadc93414c5d3b3b333b97bfaf

openstack/mistral-extra,openstack/mistral-extra