nova: Remove configuration of '[scheduler] driver'
nova: Remove configuration of '[scheduler] driver'

This option was deprecated in Ussuri [1] as nova no longer provided any
schedulers aside from the filter scheduler and the existence of
third-party schedulers was very unlikely. Stop configuring this and
simply use the default.

[1] https://review.opendev.org/#/c/707225/

Change-Id: Iabdd1d00e00ee269334f0fe0db265a97207e2dc6
Signed-off-by: Stephen Finucane <492121341a95b3c3aab646bed44634f739dd019b@redhat.com>

openstack-dev/devstack,nawawi/openstack,openstack-dev/devstack,nawawi/openstack