Resolve "Preserve test run artifacts when running gitlab-qa multiple times"

What does this MR do?

This creates the screenshots under the test group namespace, and with the same tree structure as the actual spec file.

This is the second part of https://gitlab.com/gitlab-org/gitlab-ce/issues/49021 (the first part is gitlab-qa!151 (merged)).

Why was this MR needed?

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Conform by the code review guidelines
  • Has been reviewed by a Backend maintainer
• Conform by the merge request performance guides
• Conform by the style guides
• Conform by the database guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Closes #49021 (closed)