Recently a change landed in devstack [1] to install packages into a
global venv by default and the "nova" command was not symlinked for
compat, so jobs using run-evacuate-hook are failing with:
nova: command not found
We had intended to switch away from using novaclient CLI commands in our
scripts anyway, so we can just use this opportunity to switch to OSC.
[1]: If9bc7ba45522189d03f19b86cb681bb150ee2f25
Change-Id: Ifd969b84a99a9c0460bceb1a28fcee6e51cbb4ae