SEBA-590 Comment out service downgrade b/c the core doesn't yet support reverse migrations

Change-Id: I03ec55cd84af697ac56a51ddb708d4ae0e82fa84
diff --git a/jjb/pipeline/xos-service-upgrade.groovy b/jjb/pipeline/xos-service-upgrade.groovy
index 255994c..02edeeb 100644
--- a/jjb/pipeline/xos-service-upgrade.groovy
+++ b/jjb/pipeline/xos-service-upgrade.groovy
@@ -238,6 +238,7 @@
       }
     }
 
+    /* Disable the downgrade step because the core doesn't support reverse migrations
     stage('Downgrade Service') {
       steps {
         sh """
@@ -276,6 +277,7 @@
            """
       }
     }
+    */
 
   }