Since Queens [1] nova has been able to be configured with
cinder service user credentials for operating on cinder
resources without a user auth token similar to things nova
needs to do without a user auth token for working with neutron
and placement resources.
This change:
- centralizes the nova [cinder] section configuration
- adds the necessary auth configuration
Needed by: https://review.opendev.org/549130/
[1] I3c35bba43fee81baebe8261f546c1424ce3a3383
Change-Id: I5640ee431f6856853f6b00ec7ed1ea21d05117dd