Refactor: Extract pipeline_test.py into a shared file for reuse across workflows

[akagami-harsh]

Pull Request Template for Kubeflow manifests Issues

✏️ A brief description of the changes

• extracted python code from gh action files

📦 List any dependencies that are required for this change

My PR depends on #

🐛 If this PR is related to an issue, please put the link to the issue here.

• Fix ml pipeline access from kfp step #2795 (comment)
• part of Reorganize Kubeflow tests #2797

✅ Contributor checklist

• Make sure you have tested with kustomize. See Installation Prerequisites
• All the commits have been signed-off (To pass the DCO check)

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[juliusvonkohout]

Thank you for the PR, lets see what our tests say.

[akagami-harsh]

Thank you for the PR, lets see what our tests say.

some tests are failing, ill try to fix them ASAP

[akagami-harsh]

@juliusvonkohout Could you please trigger the CI? Thanks.

[juliusvonkohout]

/lgtm
/approve

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