The [glance]api_servers config option is deprecated in nova since
I8e3fbc6f8b052ead6e80d4243f76581960210277.
The glance_endpoint_override option can be used to override the default glance
endpoint.
Support for round-robin over a list of glance servers is now deprecated in nova.
Change-Id: Ib7fac4f37ef02d8f577abc98e4cc78b750caba54