Use project_reader in compute admin tests

We have project_reader credentials in tempest and they
use the same project as member role creds. Nova support
the project reader role in get server API. Moving the
compute admin  tests to use project reader creds in GET
API calls for RBAC support.

Change-Id: I9bfb6eddae5e3d002313cc5ec2c27de38ce2ea43
Signed-off-by: Ashish Gupta <ashigupt@redhat.com>
24 files changed