The admin_* parameters are implementing the same functionality as
keystoneauth parameters alghouth these don't provide all parameters for
Keystone v3 identity but are still based on Keystone v2 identity.
This change deprecates these parameters so that we can remove
such redundant and outdated definitions in a future release.
Closes-Bug: #1927494
Change-Id: I6294098008fbebb2e64922b3aaa085c1361d48a2