Clean up code for custom CRD

[andreyvelich]

I removed redundant code and fixed tests for new custom CRD implementation.

As well, I added some default values for Job, PyTorchJob and TFJob to make examples easier for the first look, as we discussed before.

In particular, for Job:

1. Set default SuccessCondition and FailureCondition.
   I didn't add PrimaryPodLabels to Job examples since each Job has only one pod replica. If PrimaryPodLabels is omitted, metrics collector injected to all created pods.

For Kubeflow Job (PytorchJob and TFJob).

1. Set default SuccessCondition and FailureCondition.
2. Set default PrimaryPodLabels.

I manually added PrimaryContainerName to all examples. I think it is very easy to understand and user can explicitly see which container will be wrapped by metrics collector.

I can't set default values if Trial Template is set in ConfigMap, since it requires k8s client. We can think about it later.

I left validation for Job, TFJob and PyTorchJob for now. @gaocegege @johnugeorge What do you think about it ?

I deleted job/v1beta1 since it is not used. Let's continue discussion here: #1320 how we should implement MutateJob.

/assign @gaocegege @johnugeorge

[kubeflow-bot]

This change is 

[gaocegege]

/lgtm

[andreyvelich]

/retest

[gaocegege]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andreyvelich, gaocegege

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@andreyvelich: The following tests failed, say /retest to rerun all failed tests:

Test name	Commit	Details	Rerun command
kubeflow-katib-presubmit	364df94	link	/test kubeflow-katib-presubmit
kubeflow-katib-presubmit-e2e	364df94	link	/test kubeflow-katib-presubmit-e2e

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[k8s-ci-robot]

New changes are detected. LGTM label has been removed.