Make neutron-tempest-plugin-designate-scenario non voting

neutron-tempest-plugin-designate-scenario is failing 100%
with the designate new RBAC
- https://review.opendev.org/c/openstack/neutron/+/926085

This job is non voting on neutron side but voting on designate
side. And merging the requirement change
(https://review.opendev.org/c/openstack/requirements/+/925464),
will break the designate gate.

Making this job non voting for everyone until we figure out the
root cause of this failure.

Related-Bug: #2078518
Change-Id: If0f521a74ce075b408b5495a0144f01e3bcbc818

zuul.d/master_jobs.yaml

@@ -1054,6 +1054,9 @@
       - openstack/designate-dashboard
       - openstack/designate-tempest-plugin
     timeout: 3600
+    # TODO(gmann): make it voting once below bug is fixed
+    # https://bugs.launchpad.net/neutron/+bug/2078518
+    voting: false
     vars:
       network_api_extensions_common: *api_extensions
       devstack_localrc: