FIX: return 429 when admin api key is limited on admin route

This also handles a general case where exceptions leak out prior to being handled by the application controller

spec/controllers/draft_controller_spec.rb

@@ -3,7 +3,8 @@ require 'rails_helper'
 describe DraftController do
 
   it 'requires you to be logged in' do
-    expect { post :update }.to raise_error(Discourse::NotLoggedIn)
+    post :update
+    expect(response.status).to eq(403)
   end
 
   it 'saves a draft on update' do