Collect all artifacts from RSpec

What does this MR do and why?

Collect all artifacts from RSpec

Even though we're not using all of them for now, this should make it easier to debug and for update-tests-metadata to adapt the same way to consume artifacts like rspec:coverage, which we can use needs with optional: true.

This can ease looking at the reports from various jobs: gitlab-org/quality/engineering-productivity/team#272 (comment 1665560134)

How to validate

We can see we have knapsack reports in https://gitlab.com/gitlab-org/gitlab/-/jobs/5611628365/artifacts/browse/knapsack/ for all the unit tests across 24 jobs.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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