Cache specific version of gitlab-qa gem

What does this MR do?

Caches gitlab-qa gem versions so that pipelines do not rely on rubygems to be available and don't install gems from scratch in every single test job.

This mr should be merged after !192 (merged) because it changes ruby base image from alpine base to debian base and gem caches would not be compatible, so we want to start caching gem after that change is merged.

Check-list

• Verify the change in all affected pipelines.

Test run: https://ops.gitlab.net/gitlab-org/quality/staging/-/pipelines/1223846

Closes https://gitlab.com/gitlab-org/quality/team-tasks/-/issues/1333