We used to rely on keystoneclient code to get the proper endpoint from
keystone if it was not provided in the command line or as an
environment variable. This changed in a recent commit. So now that we
are using an adapter for the keystone sessions, we use the function
provided by that adapter.
Change-Id: I927a105831642d4fb00691ea2a97e27e79ebc7fd
Closes-Bug: #1443436