geo-secondary: ensure rails when Gitaly enabled

What does this MR do?

The gitaly services require configuration from gitlab_rails, so check for gitaly['enable'] in rails_needed? of geo_secondary role recipe.

Checklist

See Definition of done.

• Change added to CHANGELOG.md. Not applicable for Documentation changes and minor changes.
• Documentation created/updated Backend fix
• Tests added
• Integration tests added to GitLab QA, if applicable
• MR targeting master branch
• MR has a green pipeline on GitLab.com

Reviewer Checklist

In addition to above, reviewer must:

• Pipeline is green on dev.gitlab.org if the change is not touching documentation or internal cookbooks

References

Closes #3715 (closed)