Remove deprecated and unused nova setting.
Remove deprecated and unused nova setting.

Change-Id: I01a7c0b5faac0338594988b2e69981aad215cb33

agroup/tripleo-puppet-elements,rdo-management/tripleo-image-elements,rdo-management/tripleo-image-elements,openstack/tripleo-image-elements,openstack/tripleo-image-elements,radez/tripleo-image-elements,radez/tripleo-image-elements,agroup/tripleo-puppet-elements,agroup/tripleo-puppet-elements,agroup/tripleo-puppet-elements