If a user attempts to use basic auth, and the username/password combination
is rejected, the authenticator should return an error. This distinguishes
requests that did not provide username/passwrod (and are unauthenticated
without error) from ones that attempted to, and failed.
Kubernetes-commit: 0ec585c1395a6e380ca36fb33c6842b7aca0ea4b
This change migrates the 'openstack' provider and 'keystone'
authenticator plugin to the newer gophercloud/gophercloud library.
Note the 'rackspace' provider still uses rackspace/gophercloud.
Fixes#30404