Set designate u/s job non voting because of eventlet

A recent oslo.log patch
https://review.opendev.org/c/openstack/oslo.log/+/918426
along with Designate's usage of eventlet, made Designate
jobs unstable.

A recent bug that documents the failure was opened against Designate
https://bugs.launchpad.net/designate/+bug/2072627

In order to not block any viable tobiko patches, this patch temporarily sets Designate jobs as non voting.

Change-Id: I8903ddb92f50936ffbfca2abc6f7ebde82302d2a

zuul.d/devstack-tobiko-designate.yaml

@@ -20,7 +20,7 @@
 - job:
     name: devstack-tobiko-designate
     parent: devstack-tobiko
-    voting: true
+    voting: false
     required-projects: &REQUIRED_PROJECTS
       - opendev.org/openstack/designate
       - opendev.org/openstack/python-designateclient
@@ -34,6 +34,6 @@
 - job:
     name: devstack-tobiko-ovs-designate
     parent: devstack-tobiko-ovs
-    voting: true
+    voting: false
     required-projects: *REQUIRED_PROJECTS
     vars: *VARS