Enable routing service by default in GDK

What does this merge request do and why?

We added gitlab-http-router in gitlab#450958 (closed), disabled by default.

Now, we're enabling it by default.

How to set up and validate locally

1. Checkout the branch
2. If applicable, remove the current http_router configuration from the gdk.yml file
3. Run gdk reconfigure
4. Run gdk restart
5. Verify that HTTP router is up and running 🎉

Impacted categories

The following categories relate to this merge request:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Merge request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise an issue to follow-up.
• Documentation added/updated, if needed.
• Announcement added, if change is notable.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.

Closes #2102 (closed)