Magnum, Cinder and Octavia clients in Magnum now use endpoint_type of
internalURL by default consistent with other clients also used by the
conductor. Additionally, they also use the globally defined
`openstack_region_name` for region_name.

Closes-Bug: #1885096

Change-Id: Ibec511013760cc4f681a2ec1b769b532be3daf2d