CI: Make kayobe-overcloud-upgrade-slurp-rocky9 non-voting

The kayobe-overcloud-upgrade-slurp-rocky9 job has been failing very
frequently [1], mostly during post-upgrade bare metal testing. The Tenks
VM usually fails to get an IP address via DHCP. Make job non-voting
until we fix the issue.

[1] https://zuul.opendev.org/t/openstack/builds?job_name=kayobe-overcloud-upgrade-slurp-rocky9&project=openstack/kayobe

Change-Id: I3bb91696b54812dcfb831ac2715836acc1ee1e6b

zuul.d/project.yaml

@@ -25,7 +25,9 @@
         - kayobe-overcloud-host-configure-ubuntu-noble
         - kayobe-overcloud-upgrade-rocky9
         - kayobe-overcloud-upgrade-ubuntu-noble
-        - kayobe-overcloud-upgrade-slurp-rocky9
+        # TODO(priteau): Fix and enable before release
+        - kayobe-overcloud-upgrade-slurp-rocky9:
+            voting: false
         - kayobe-seed-rocky9
         - kayobe-seed-rocky9-podman
         - kayobe-seed-ubuntu-noble
@@ -59,7 +61,6 @@
         - kayobe-overcloud-host-configure-ubuntu-noble
         - kayobe-overcloud-upgrade-rocky9
         - kayobe-overcloud-upgrade-ubuntu-noble
-        - kayobe-overcloud-upgrade-slurp-rocky9
         - kayobe-seed-rocky9
         - kayobe-seed-rocky9-podman
         - kayobe-seed-ubuntu-noble