Remove openshift-sdn-based CI jobs by 4.17 (os-image-provider)

openshift-sdn is no longer supported for new installs as of 4.15, and it will be completely removed from OpenShift in 4.17.

Your component currently has one or more CI jobs that use openshift-sdn:

ci-operator/config/openshift/image-customization-controller/openshift-image-customization-controller-main.yaml
  e2e-metal-ipi-sdn-bm
  e2e-metal-ipi-serial-ipv4

ci-operator/config/openshift/machine-os-images/openshift-machine-os-images-main.yaml
  e2e-metal-ipi-serial-ipv4

These jobs will need to be removed or migrated to ovn-kubernetes by OCP 4.17. In some cases, if you were not intentionally testing openshift-sdn, it may make sense to start migrating these jobs in 4.15. You may want to split this bug into multiple bugs for different OCP versions.

Component-specific notes:

• image-customization-controller uses the common pattern of testing baremetal with sdn+ipv4 (e2e-metal-ipi-sdn-bm) and ovn+ipv6 (e2e-metal-ipi-ovn-ipv6). Depending on your testing needs, it may make sense to remove the sdn+ipv4 job and keep just the ovn+ipv6 one, or to replace the sdn+ipv4 job with ovn+ipv4, or to replace both jobs with a single ovn+ipv4 job.
• In both repos, e2e-metal-ipi-sdn-serial-ipv4 is the only serial job and presumably did not intend to be testing against sdn, and thus should probably be rebased onto the (new) baremetalds-e2e-serial-ovn-ipv4 workflow.