E2E test: migrate MR related HAML selectors to testid

What does this MR do and why?

Partially resolves #415284 (closed)

Migrates data-qa-selectors to data-testid for MR-related HAML files.

How to set up and validate locally

Probably best to view a passing pipeline

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.