Revert "FEATURE: add Noindex to robots.txt for disallowed routes"

This reverts commit d84256a876.

This is not supported by Google and causes robots.txt to be flagged as
invalid

Removing Noindex

app/views/robots_txt/index.erb

@@ -10,7 +10,6 @@ Crawl-delay: <%= agent[:delay] %>
 <%- end -%>
 <% agent[:disallow].each do |path| %>
 Disallow: <%= path %>
-Noindex: <%= path %>
 <% end %>
 
 

spec/requests/robots_txt_controller_spec.rb

@@ -20,7 +20,6 @@ RSpec.describe RobotsTxtController do
         Discourse.stubs(:base_uri).returns('/forum')
         get '/robots.txt'
         expect(response.body).to include("\nDisallow: /forum/admin")
-        expect(response.body).to include("\nNoindex: /forum/admin")
       end
     end