use openshift client image from redhat registry for node-labeler job

[dlbewley]

Use the OpenShift client image from Red Hat registry rather than assuming the local cluster registry has already been deployed with an alternative storage back end.

[pittar]

Although I see your point @dlbewley , your change now assumes clusters have access to the Red Hat registry.
I'm ok with this change for now, but perhaps we should add an overlay for the internal registry as well.

[dlbewley]

Fair, but if the cluster is disconnected (without access to Red Hat registry), there will have been accommodations made to mirror the RH registry or to proxy the pulls from it in order to install the cluster.

This automation exists to facilitate storage which in on-prem cases is very likely prerequisite to an internal registry. See also #233