tempest: Use primary user token

This change uses an non-admin user for the autoscaling tests.

This should avoid future bug like
https://bugs.launchpad.net/aodh/+bug/1703824

Change-Id: Ia8b5244aee9b6fedb9f205c32fef968e12061e37
diff --git a/ceilometer/tests/integration/gabbi/gabbits-live/autoscaling.yaml b/ceilometer/tests/integration/gabbi/gabbits-live/autoscaling.yaml
index 3670925..8eac9d0 100644
--- a/ceilometer/tests/integration/gabbi/gabbits-live/autoscaling.yaml
+++ b/ceilometer/tests/integration/gabbi/gabbits-live/autoscaling.yaml
@@ -1,6 +1,6 @@
 defaults:
     request_headers:
-        x-auth-token: $ENVIRON['ADMIN_TOKEN']
+        x-auth-token: $ENVIRON['USER_TOKEN']
 
 tests:
     - name: list alarms none