compute: Remove references to optional extensions
compute: Remove references to optional extensions

This is no longer a thing in nova.

Change-Id: I2413b826385792a4f33ff70e75621b48de65c799
Signed-off-by: Stephen Finucane <492121341a95b3c3aab646bed44634f739dd019b@redhat.com>

openstack/python-openstackclient,openstack/python-openstackclient