Remove OpenShift example due to auto-detection

With OpenShift auto-detection a specific example for OpenShift is no
longer required.

Author: jmckulk

kustomize/keycloak/postgres.yaml

@@ -5,7 +5,6 @@ metadata:
 spec:
   image: registry.developers.crunchydata.com/crunchydata/crunchy-postgres-ha:centos8-13.3-0
   postgresVersion: 13
-  openshift: false
   instances:
     - replicas: 2
       dataVolumeClaimSpec: