Add categories for katib CRDs

[hougangliu]

# kubectl get katib -n kubeflow-test
NAME                STATUS      AGE
random-experiment   Succeeded   23h

NAME                         STATUS      AGE
random-experiment-4x8q6r6d   Succeeded   23h
random-experiment-5bvj7rrz   Succeeded   23h

# kubectl get kubeflow -n kubeflow-test
NAME                STATUS      AGE
random-experiment   Succeeded   23h

NAME                         STATUS      AGE
random-experiment-4x8q6r6d   Succeeded   23h
random-experiment-5bvj7rrz   Succeeded   23h

# kubectl get experiments -n kubeflow-test
NAME                STATUS      AGE
random-experiment   Succeeded   23h

# kubectl get trials -n kubeflow-test
NAME                         STATUS      AGE
random-experiment-4x8q6r6d   Succeeded   23h
random-experiment-5bvj7rrz   Succeeded   23h

---

This change is 

[hougangliu]

/test kubeflow-katib-presubmit

[hougangliu]

/cc @gaocegege @johnugeorge @richardsliu

[gaocegege]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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