Update deprecated env properties for KUBE_PING

As reported and discovered by QE (mchoma@redhat.com):

In 'USING JBOSS EAP ON OPENSHIFT CONTAINER PLATFORM' e.g. https://jenkins.dxp.redhat.com/job/CCS/job/ccs-mr-preview/69151/artifact/eap-for-openshift/preview/index.html we are documenting OPENSHIFT_KUBE_PING_LABELS and OPENSHIFT_KUBE_PING_NAMESPACE.

These were replaced by more generic KUBERNETES_NAMESPACE and KUBERNETES_LABELS - see
https://github.com/jgroups-extras/jgroups-kubernetes/blob/main/README.adoc - so the documentation should be updated accordingly.