Description of problem:

 - Customer has followed steps in documentation for migrating MTU on nodes (and has followed guidance from Red Hat, stepping through these steps together to ensure they are followed correctly):
https://docs.openshift.com/container-platform/4.12/networking/changing-cluster-network-mtu.html

• Migration steps concluded, including step 9 to patch remove migration + update MTU and we see this message:

'Not applying unsafe configuration change: invalid configuration: [cannot change ovn-kubernetes MTU without migration]. Use ''oc edit network.operator.openshift.io   cluster'' to undo the change.

Currently the network.operator.openshift.io object looks like so:

spec:
  clusterNetwork:
  - cidr: 172.16.0.0/12
    hostPrefix: 23
  defaultNetwork:
    ovnKubernetesConfig:
      egressIPConfig: {}
      gatewayConfig:
        routingViaHost: false
      genevePort: 6081
      mtu: 1400
      policyAuditConfig:
        destination: "null"
        maxFileSize: 50
        rateLimit: 20
        syslogFacility: local0
    type: OVNKubernetes
  deployKubeProxy: false
  disableMultiNetwork: false
  disableNetworkDiagnostics: false
  logLevel: Normal
  managementState: Managed
  observedConfig: null
  operatorLogLevel: Normal
  serviceNetwork:
  - 192.168.0.0/16
  unsupportedConfigOverrides: null
  useMultiNetworkPolicy: false
status:
  conditions:
  - lastTransitionTime: "2023-11-28T05:43:32Z"
    status: "False"
    type: ManagementStateDegraded
  - lastTransitionTime: "2024-02-09T12:26:02Z"
    message: 'Not applying unsafe configuration change: invalid configuration: [cannot
      change ovn-kubernetes MTU without migration]. Use ''oc edit network.operator.openshift.io
      cluster'' to undo the change.'
    reason: InvalidOperatorConfig
    status: "True"
    type: Degraded

Looking at the machine-config update history, we can see that the migration was triggered automatically and `migrate-mtu.sh` was added automatically, then subsequently the machine-configs applied from butane were added (and a subsequent machine-config rollout applied them + removed migrate-mtu.sh")

This appears to be a failure on the removal of MIGRATION block + update of MTU for the cluster itself only, nodes are all in desired (higher) MTU values.

Currently blocked/cluster impacted as a result of mismatched MTU.

Version-Release number of selected component (if applicable):

How reproducible:
 

Steps to Reproduce:

1. Follow documentation to increase MTU on target cluster

2. Validate configrations and files + apply them as outlined

3. observe cluster stall + degraded CNO as a result of still-reduced MTU value due to missing migration block (removed by the patch command, but MTU change apply failed to follow).

Actual results:

degraded cluster
 

Expected results:

 migrated MTU successfully is expected
Additional info:

additional data to follow in next update with template request.