Add end-to-end test for External platform

Background

To ensure we are properly testing the new External platform we will need to add an E2E test. This test should essentially be a copy of our current None platform test. Currently the None platform tests run on vSphere.

Steps

• copy None test to use External platform
• create a new step in ci-operator to modify an infrastructure config to use platform external
• create a new workflow/chain that uses the following:
  • upi-conf-vsphere-platform-none, to create the initial install configuration
  • upi-conf-vsphere, to create the manifest files
  • the new step to modify the infrastructure manifest
  • upi-install-vsphere, to run the installation
• create a periodic job to exercise the new workflow, this should be once a week to begin with

Stakeholders

• openshift eng

Definition of Done

• Test pipeline is established for External platform

• Docs

• n/a

• Testing

• n/a