Upload artifacts with `/var/logs/gitlab` in case of QA test failures

Description

It would be super helpful to be able to access GitLab logs in case of a failure in QA pipeline.

Currently we only upload screenshots generated by Capybara, but we can easily bind-mount the /var/logs/gitlab directory and send artifacts with logs as well.

It would be much easier to debug problems like https://gitlab.com/gitlab-org/gitlab-qa/-/jobs/40438277

Cloning into '.'...
error: RPC failed; result=22, HTTP code = 500
fatal: The remote end hung up unexpectedly

with access to the logs.

/cc @rymai