zuul: Temporarly put Centos9 Stream job non-voting
zuul: Temporarly put Centos9 Stream job non-voting

Due to the bug below, all the nova patches are failing. I accordingly
propose to make the job non-voting as it would allow our gate to ressurect.

Of course, this is a transient solution and we need a proper fix for the
job in order to have Centos 9 Stream support back in place ASAP.

When the job is back OK, please make it voting again by reverting this patch.

Change-Id: I5c3fff65fd6d9e4f3632d1ec62ae3f1f9cfbe626
Related-Bug: #1979047

openstack/nova,mahak/nova,openstack/nova,mahak/nova,mahak/nova,openstack/nova