Change build node for multicloud openstack jjb

The new build node is expected to launch py3 by default

Change-Id: Ib02e8a3b51e5d7c017dfe6d2760666ce6181dbe2
Issue-ID: MULTICLOUD-763
Signed-off-by: Bin Yang <bin.yang@windriver.com>
diff --git a/jjb/multicloud/multicloud-openstack.yaml b/jjb/multicloud/multicloud-openstack.yaml
index 9d6e58a..bc73f9d 100644
--- a/jjb/multicloud/multicloud-openstack.yaml
+++ b/jjb/multicloud/multicloud-openstack.yaml
@@ -75,7 +75,7 @@
           container-staging-registry: 'nexus3.onap.org:10003'
     files: '**'
     archive-artifacts: ''
-    build-node: 'ubuntu1604-memcached-4c-4g'
+    build-node: 'centos7-memcached-4c-4g'
 
 #- project:
 #    name: multicloud-openstack-arm64