Fix problem using HTTP router with NGINX HTTPS configured

What does this merge request do and why?

Previously NGINX listened for HTTP traffic on port 8080 and redirected this to its HTTP port, 3443. With !3756 (merged), the router listens to port 3443, terminates SSL, and communicates internally with NGINX on port 8080. This means that we need to disable this HTTP->HTTPS redirection for now if the HTTP router is used.

How to set up and validate locally

1. Configure your gdk.yml to enable NGINX with HTTPS (https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/main/doc/howto/nginx.md):

nginx:
  enabled: true
  http2:
    enabled: true
  ssl:
    certificate: "/Users/stanhu/gdk-ee/nginx/host.docker.internal.pem"
    key: "/Users/stanhu/gdk-ee/nginx/host.docker.internal-key.pem"

2. Run gdk reconfigure.
3. Run gdk restart nginx
4. Run gdk restart gitlab-http-router

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.