Added test for create-pytorchjob.ipynb python notebook

[saileshd1402]

What this PR does / why we need it: This PR addresses the issue: https://github.com/kubeflow/training-operator/issues/2246

Changes:

• Added test for examples/pytorch/image-classification/create-pytorchjob.ipynb using papermill
• Made it extendable so that new notebooks can be added easily
• New notebook tests can be added to the test-example-notebooks.yaml file/workflow as jobs
• Notebook tests should have the parameter kubeflow_python_sdk so that CI will install local Python SDK for testing
• Updated gcr.io/kubeflow-ci/pytorch-dist-mnist-test:v1.0 to kubeflow/pytorch-dist-mnist:latest

Checklist:

• [ ] Docs included if any changes are user facing

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[coveralls]

Pull Request Test Coverage Report for Build 11096923156

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 11001381410:	0.0%
Covered Lines:	66
Relevant Lines:	66

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💛 - Coveralls