Improve MySQL Galera password handling - use dedicated not root credentials

Prod related PROD-23926 (PROD:23926)

Change-Id: I1c09b54e22ac274336597fff6582a5b997f13ea4
diff --git a/tests/pillar/slave_cluster.sls b/tests/pillar/slave_cluster.sls
index 390f09b..458f09a 100644
--- a/tests/pillar/slave_cluster.sls
+++ b/tests/pillar/slave_cluster.sls
@@ -147,6 +147,9 @@
     admin:
       user: root
       password: password
+    sst:
+      user: sstuser
+      password: sstpassword
     members:
     - host: 127.0.0.1
       port: 4567
@@ -182,3 +185,12 @@
       password: password
       database: '*.*'
       grants: PROCESS
+    - name: sstuser
+      password: sstpassword
+      host: localhost
+      database: '*.*'
+      grants:
+        - PROCESS
+        - RELOAD
+        - LOCK TABLES
+        - REPLICATION CLIENT