To run disconnected cluster testing with final release candidate on stage.

• Provision disconnected cluster via install-ocp-upi job
• Mirror images via mirror-index-image-plugin job
  • Make sure you set correct BOOKINFO_TAG, according to bookinfo tags used in kiali
  • Make sure that all images for ossm3 defined here are still valid in test suites (if some images were changed in test suited, extend/update that script)
• Run downstream pipeline with disconnected mode and with Kiali integration and Sail e2e tests
  • Some tests can fail due to missing images in bastion (ImagePullBackOff). In that case, identify the images, extend the mirroring scripts about them and mirror them in bastion