Revert "Move default Keystone API version to v3"

It seems like the fallout from this was not well sorted.
A lot of things aren't working, and there is still vestigial
v2 bits left behind.

This should have come with a much greater warning and some
spot checking of additional services working with this.

This reverts commit b162a1d58cdecfb32847b59bd341e06c26efb1ed.

Change-Id: Ia792b23119c00089542ba08879dca1c29dc80945
diff --git a/lib/tempest b/lib/tempest
index 4a289fa..3c34aad 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -259,7 +259,6 @@
     # Identity
     iniset $TEMPEST_CONFIG identity uri "$KEYSTONE_SERVICE_PROTOCOL://$KEYSTONE_SERVICE_HOST:5000/v2.0/"
     iniset $TEMPEST_CONFIG identity uri_v3 "$KEYSTONE_SERVICE_URI_V3"
-    iniset $TEMPEST_CONFIG identity auth_version ${TEMPEST_AUTH_VERSION:-v3}
     if [[ "$TEMPEST_HAS_ADMIN" == "True" ]]; then
         iniset $TEMPEST_CONFIG auth admin_username $ADMIN_USERNAME
         iniset $TEMPEST_CONFIG auth admin_password "$password"
@@ -270,6 +269,10 @@
     if [ "$ENABLE_IDENTITY_V2" == "False" ]; then
         # Only Identity v3 is available; then skip Identity API v2 tests
         iniset $TEMPEST_CONFIG identity-feature-enabled api_v2 False
+        # In addition, use v3 auth tokens for running all Tempest tests
+        iniset $TEMPEST_CONFIG identity auth_version v3
+    else
+        iniset $TEMPEST_CONFIG identity auth_version ${TEMPEST_AUTH_VERSION:-v2}
     fi
 
     if is_ssl_enabled_service "key" || is_service_enabled tls-proxy; then