Cannot specify endpoint type when managing glance cache

[Kairat Kushaev]

When we pass internalURL for glance-cache-manage by exporting environment variable "GLANCE_ENDPOINT_TYPE=internalURL",
it doesn't get the endpoint for internalURL from glance, rather it gets public endpoint.

The code snippet from the below link:

https://github.com/openstack/glance/blob/stable/mitaka/glance/common/auth.py#L215-L217

Here while retrieving endpoint for glance service, there is no feasibility to pass endpoint_type, so it fetches by default endpoint_type which is publicURL. In most cases cache manage and other APIs communicates with internalURL/adminURL only and should not communicate to publicURL. So it is required to allow users to specify which endpoint to choose.