Verified as follows - undercloud nova.conf has the correct configurations.
instack-undercloud.noarch 6.0.0-6.el7ost @rhelosp-11.0-puddle
[stack@undercloud-0 ~]$ sudo grep "instance_usage_audit" /etc/nova/nova.conf
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.