denylist: add ostree.sync on all arches

That test is currently hitting issues when composefs is re-enabled:

#1744

While we look into it, let's denylist it so we get more composefs
testing downstream.

Note there's already another entry for that same test on s390x, but
let's keep them separate since they seem to be separate issues.

Author: jlebon

kola-denylist.yaml

@@ -45,3 +45,6 @@
   warn: true
   arches:
     - s390x
+
+- pattern: ostree.sync
+  tracker: https://github.com/openshift/os/issues/1744