Turn off tenant_isolation in tempest for quantum

Current tempest didn't create networks for each tenant, so let
tempest use demo tenant for tesing if we enable quantum.

Change-Id: I5f139b5f1bdf5c176130b8db9e896e2cb48b4420
diff --git a/lib/tempest b/lib/tempest
index 1859921..a9a05ee 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -187,6 +187,12 @@
     iniset $TEMPEST_CONF compute resize_available False
     iniset $TEMPEST_CONF compute change_password_available False
     iniset $TEMPEST_CONF compute compute_log_level ERROR
+    # Note(nati) current tempest don't create network for each tenant
+    # so reuse same tenant for now
+    if is_service_enabled quantum; then
+        TEMPEST_ALLOW_TENANT_ISOLATION=${TEMPEST_ALLOW_TENANT_ISOLATION:-False}
+    fi
+    iniset $TEMPEST_CONF compute allow_tenant_isolation ${TEMPEST_ALLOW_TENANT_ISOLATION:-True}
     #Skip until #1074039 is fixed
     iniset $TEMPEST_CONF compute run_ssh False
     iniset $TEMPEST_CONF compute ssh_user ${DEFAULT_INSTANCE_USER:-$OS_USERNAME}