Update Auto DevOps demo to make it work with latest codeclimate version

Auto DevOps demo application (https://gitlab.com/auto-devops-examples/minimal-ruby-app) relies on the fixme CodeClimate engine to spot a code quality problem and allow to fix and show the improvement in the MR widget.

With CodeClimate 0.70.0 this engine is not automatically loaded, so the script is not working.

We should find a way to use a different story that works well, or force the fixme engine to on in Auto DevOps template.