Support fast-quarantine feature

What does this MR do and why?

This supports https://gitlab.com/gitlab-org/gitlab/-/merge_requests/119555 by mounting qa/rspec to /home/gitlab/qa/rspec, and forwarding RSPEC_FAST_QUARANTINE_PATH & RSPEC_SKIPPED_TESTS_REPORT_PATH variables.

MR acceptance checklist

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