This will make it clearer why a gitaly-ruby `bundle check`
failed. Currently there is an implicit assumption that jobs in the test
stage will run within 24 hours of the `setup-test-env` step
running. However, if a test runs after that time frame, the CI artifacts
will have been destroyed, and the `tmp/tests` directory won't contain
the right data.

This happened in https://gitlab.com/gitlab-org/gitlab/-/jobs/371020233.
The gitaly-ruby `bundle check` quietly failed because
`tmp/tests/gitaly-ruby/Gemfile` didn't exist. At first, we thought
`bundle check` failed because of a stale cache or a missing Gem.