Save test OAuth GitLab container logs

What does this MR do and why?

This adds logging to qa/specs/features/browser_ui/10_govern/login/login_via_oauth_and_oidc_with_gitlab_as_idp_spec.rb to save the GitLab logs for the GitLab instance used as the OAuth server.

The aim is to check if any of those logs help figure out the failures in #415011 (closed) and #429723 (closed).

How to set up and validate locally

From the qa directory:

bundle install
bundle exec bin/qa Test::Instance::All http://gdk.test:3000 -- qa/specs/features/browser_ui/10_govern/login/login_via_oauth_and_oidc_with_gitlab_as_idp_spec.rb

When the test finishes the test framework logging should have an entry like:

[Oct 31 2023 06:42:46 UTC (QA Tests)] INFO  -- Executing: `docker cp gitlab-oidc-consumer:/var/log/gitlab /home/gitlab/qa/tmp/gitlab-oidc-consumer`

And you should find GitLab logs in the tmp folder.

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.