Switch devstack to use qcow cirros img

This commit switches devstack to use the published qcow2 cirros image
instead of the AMI version. Using AMI was mostly a historical artifact
dating pretty far back, but in the real world no one really uses AMI
images with openstack clouds. This change reflects that and also
enables tempest ro remove its deprecated config options for using AMI
as a fallback on misconfiguration (which was just there to support
devstack's defaults)

Change-Id: Id65ebae73b28da7185cb349b714b659af51ef77f
diff --git a/lib/tempest b/lib/tempest
index 937436d..108256e 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -415,14 +415,11 @@
         iniset $TEMPEST_CONFIG scenario img_disk_format vhd
         iniset $TEMPEST_CONFIG scenario img_container_format ovf
     else
-        SCENARIO_IMAGE_DIR=${SCENARIO_IMAGE_DIR:-$FILES/images/cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-uec}
-        SCENARIO_IMAGE_FILE="cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-disk.img"
+        SCENARIO_IMAGE_DIR=${SCENARIO_IMAGE_DIR:-$FILES}
+        SCENARIO_IMAGE_FILE=$DEFAULT_IMAGE_NAME
     fi
     iniset $TEMPEST_CONFIG scenario img_dir $SCENARIO_IMAGE_DIR
     iniset $TEMPEST_CONFIG scenario img_file $SCENARIO_IMAGE_FILE
-    iniset $TEMPEST_CONFIG scenario ami_img_file "cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-blank.img"
-    iniset $TEMPEST_CONFIG scenario ari_img_file "cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-initrd"
-    iniset $TEMPEST_CONFIG scenario aki_img_file "cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-vmlinuz"
 
     # If using provider networking, use the physical network for validation rather than private
     TEMPEST_SSH_NETWORK_NAME=$PRIVATE_NETWORK_NAME