Add ability to provide extra parameters to config

This commit replicates Ic44a8214d82956c3f2b9ccbd0e4a797cfe6cb97f to all
available distributions and all releases after Mitaka

Change-Id: Ia70b2334f1b6f7836e4095aea897f35e6f61f7fd
diff --git a/tests/pillar/cluster.sls b/tests/pillar/cluster.sls
index c6d7cc6..bef5d37 100644
--- a/tests/pillar/cluster.sls
+++ b/tests/pillar/cluster.sls
@@ -49,3 +49,6 @@
         description: "Test domain"
         identity:
           list_limit: 20
+    extra_config:
+      federation:
+        cache_group_membership_in_db: true