As part of OCPBUGS-18641 we have created a code that appends internal OVN-K8s subnet `fd69::2/128` to the `ExcludeNetworkSubnetCIDR` list for dual-stack installations.

What has been discovered now is that for IPv6-only clusters this network is not present on this list even though it should be.

This is causing vSphere IPv6-only setups to work incorrectly.