Using the common function to configure keystoneauth middleware leaves
some options not actually used for service-to-service communication.
Create a dedicated function, which configures only options loaded by
keystoneauth library, to drop unnecessary options.
Change-Id: Idafdd4a3925d09f155d8ec651786ccbcd6a5f2e4
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>