Ensure CCCMO does not react to External platform type

Background

As described in the external platform enhancement , the cluster-cloud-controller-manager-opeartor should be modified to react to the external platform type in the same manner as platform none.

Steps

• add an extra clause to the platform switch that will group "External" with "None"

Stakeholders

• openshift eng

Definition of Done

• CCCMO behaves as if platform None when External is selected

• Docs

• developer docs for CCCMO should be updated

• Testing

• see OCPCLOUD-1782