Unhardcoding libvirt group name parameter for socket. Upgrade path

Change-Id: Ia7c9c871a87664ed23a67e14bbc5ea91729e0c3d
diff --git a/tests/pillar/compute_cluster.sls b/tests/pillar/compute_cluster.sls
index 58f98ef..1a3335f 100644
--- a/tests/pillar/compute_cluster.sls
+++ b/tests/pillar/compute_cluster.sls
@@ -68,3 +68,4 @@
       hw_disk_discard: unmap
     upgrade_levels:
       compute: liberty
+    libvirt_service_group: libvirtd