[feed manager] Gut the feed manager

app/controllers/api/v1/account_by_username_controller.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class Api::V1::AccountByUsernameController < API::BaseController
+class Api::V1::AccountByUsernameController < EmptyController
   before_action :set_account
   before_action :check_account_suspension
   before_action :check_account_local

app/controllers/empty_controller.rb

@@ -42,7 +42,7 @@ class EmptyController < ActionController::Base
     links << [prev_path, [%w(rel prev)]] if prev_path
     response.headers['Link'] = LinkHeader.new(links) unless links.empty?
   end
-  
+
   def current_user
     nil
   end
@@ -55,6 +55,10 @@ class EmptyController < ActionController::Base
     nil
   end
 
+  def gone
+    respond_with_error(410)
+  end
+
   def cache_collection(raw, klass)
     return raw unless klass.respond_to?(:with_includes)
 
@@ -83,6 +87,6 @@ class EmptyController < ActionController::Base
   def truthy_param?(key)
     ActiveModel::Type::Boolean.new.cast(params[key])
   end
-  
+
 
 end