fix: correct cleanPodPolicy default in generated docs

[immanuwell]

Problem

SetDefaults_MPIJob defaults omitted cleanPodPolicy to None, but the shipped CRD, deploy yaml, swagger, and python sdk docs say Running.
That is a pretty easy footgun in the wild.

Fix

Update the source comment and regenerate the published API surfaces so they all say Defaults to None.

Repro

1. Open pkg/apis/kubeflow/v2beta1/default.go and see policy.CleanPodPolicy = ptr.To(CleanPodPolicyNone).
2. Open the pre-fix generated docs, for example deploy/v2beta1/mpi-operator.yaml, and see Default to Running.
3. Omit spec.runPolicy.cleanPodPolicy in an MPIJob. The real default is None, so the docs were off.

Validation

go test ./pkg/apis/kubeflow/v2beta1 ./pkg/apis/kubeflow/validation ./pkg/controller

[google-oss-prow]

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[tenzen-y]

@immanuwell Thank you for your contribution, it seems that generated codes are out dated. Can you verify and fix that?

https://github.com/kubeflow/mpi-operator/actions/runs/28703199713/job/85237964347?pr=827