request for this work came from this slack thread

looks like the below two config changes need to be made post-install:

for subnet:

apiVersion: operator.openshift.io/v1
kind: Network
metadata:
  name: cluster
spec:
  defaultNetwork:
    ovnKubernetesConfig:
      gatewayConfig:
        ipv4:
          internalMasqueradeSubnet: 100.254.169.0/29

for transit switch:

apiVersion: operator.openshift.io/v1
kind: Network
metadata:
  name: cluster
spec:
  defaultNetwork:
    ovnKubernetesConfig:
      ipv4:
        InternalJoinSubnet: "100.99.0.0/16"

doing this work can be it's own new ci-operator/step-registry workflow. An
example to look at is the cidr-expansion workflow.

we can create an entire new job for this work, but another idea could be to create a new "day 2 operations" job and include this workflow and others (e.g., cidr-expansion). The flow would be:

1. install cluster
2. run each day 2 workflow
   1. each workflow should include it's own validations so that if there is a problem or regression then that step would fail
3. run normal e2e suite