Remove legacy-routes-service from web-routes.conf

We removed the legacy-routes-service starting in puppetserver 7, but we never removed it from web-routes.conf: https://github.com/puppetlabs/puppetserver/blob/42d96b68f4219b9dc90630addbd0f97f0f7f3bc2/ezbake/config/conf.d/web-routes.conf#L6

We should remove it, since it's confusing to ship a config file that mentions an unsupported service.

Ensure corresponding docs are updated: https://puppet.com/docs/puppet/7/server/config_file_web-routes.html