Add QA test to verify unlocking of job artifacts across pipelines

What does this MR do and why?

Add QA test to verify unlocking of job artifacts across pipelines.

We have had a number of issues related to unlocking of job artifacts after pipelines are completed in various statuses. For example:

1. When pipeline failed: #266958 (closed)
2. When pipeline is blocked: #387087 (closed)

This sets up a QA test for the initial working scenario, where a pipeline that completes successfully would unlock the job artifacts from previous successful pipelines.

Screenshots or screen recordings

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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