Change ActivityPub paging to match spec. Clean up ActivityPub outbox changes. (#2410)

* Change ActivityPub paging to match spec. Clean up ActivityPub outbox changes.

* Fix code style and test failures for OutboxController.

* Attempt to fix CI errors.

app/controllers/accounts_controller.rb

@@ -15,9 +15,7 @@ class AccountsController < ApplicationController
         render xml: AtomSerializer.render(AtomSerializer.new.feed(@account, @entries.to_a))
       end
 
-      format.activitystreams2 do
-        headers['Access-Control-Allow-Origin'] = '*'
-      end
+      format.activitystreams2
     end
   end