Remove Horizon setup scripts usage of run_tests.sh
Remove Horizon setup scripts usage of run_tests.sh

Horizon is removing run_tests in favour of tox during Ocata, as part of
https://blueprints.launchpad.net/horizon/+spec/enhance-tox. To complete
this move, we need to remove any reliance on run_tests.

Change-Id: Ia8ad073aee68d1660d3bb5a68ec07516d8ce0665

group-policy/devstack,noironetworks/devstack,bswartz/devstack,bswartz/devstack,openstack-dev/devstack,richliu/devstack,nawawi/openstack,dtroyer/devstack,openstack-dev/devstack,richliu/devstack,group-policy/devstack,nawawi/openstack,dtroyer/devstack,noironetworks/devstack