Shrink/Reduce clusterNetwork CIDR post-installation in OpenShift cluster

1. Proposed title of this feature request
Shrink clusterNetwork CIDR post-installation

2. What is the nature and description of the request?
Cluster administrators should be able to shrink/reduce the clusterNetwork CIDR , the same way that Redhat supports expanding the clusterNetwork CIDR

3. Why does the customer need this? (List the business requirements here)
Refer comment section of RFE for details.

4. List any affected packages or components.