nova-manage: squash oslo_policy debug logging
nova-manage: squash oslo_policy debug logging

I don't know when it started but you can see from a modern
usage of nova-manage that oslo_policy debug logging is being
emitted. We don't need that debug information in the console
for nova-manage, so this patch hides it just like we do for
oslo_db.

Change-Id: If1a8e8d473846f2626f5e01210f00ad06916a383
Related-Bug: #1650694

mikalstill/nova,jianghuaw/nova,openstack/nova,mahak/nova,phenoxim/nova,gooddata/openstack-nova,phenoxim/nova,vmturbo/nova,gooddata/openstack-nova,klmitch/nova,rajalokan/nova,hanlind/nova,klmitch/nova,jianghuaw/nova,rahulunair/nova,jianghuaw/nova,klmitch/nova,Juniper/nova,Juniper/nova,vmturbo/nova,openstack/nova,mahak/nova,openstack/nova,mikalstill/nova,vmturbo/nova,vmturbo/nova,mahak/nova,hanlind/nova,jianghuaw/nova,gooddata/openstack-nova,gooddata/openstack-nova,hanlind/nova,rajalokan/nova,rahulunair/nova,Juniper/nova,rajalokan/nova,Juniper/nova,mikalstill/nova,klmitch/nova,rahulunair/nova,rajalokan/nova