CI: Mark OpenSearch as non voting

It's been failing since 2.13

Change-Id: I8e7ed01707ef6956ca6fff4c2f4ca0cd68ee252b

zuul.d/base.yaml

@@ -248,6 +248,7 @@
 - job:
     name: kolla-ansible-prometheus-opensearch-base
     parent: kolla-ansible-base
+    voting: false
     files:
       - ^requirements-core.yml
       - ^ansible/roles/(common|opensearch|grafana|prometheus)/