Disabling a service in Procfile/gdk.yml does not remove it, and `gdk start` still starts it

Problem

1. gdk install
2. gdk status
3. See that jaeger service is available (though not started)
4. Disable jaeger. Add to gdk.yml:

   tracer:
     jaeger:
       enabled: false

5. rm Procfile && make Procfile
6. gdk start

See that jaeger becomes started, because the services/jaeger symlink still exists.

Possible solutions

I'm not sure. Make Runit.sv() remove services if they don't exist in the Procfile?

Also

Following the old directions (which have since been modified to workaround this issue) in https://gitlab.com/gitlab-org/gitlab-development-kit/blob/master/doc/howto/geo.md#secondary, this caused a fresh Geo secondary to die after a while because the second instance of Jaeger conflicts with the first one on the same port, and its health checks will keep failing.