Add record to track overridden limits

Before, we were relying on just changing the cards_count in account, but this
could create problems where the system to calculate the next card number fails due
to the unique constraint.

saas/test/controllers/admin/stats_controller_test.rb

@@ -1,10 +1,6 @@
 require "test_helper"
 
 class Admin::StatsControllerTest < ActionDispatch::IntegrationTest
-  def saas
-    Fizzy::Saas::Engine.routes.url_helpers
-  end
-
   test "staff can access stats" do
     sign_in_as :david