Silence unnecessary warning about sqlite3

This test uses sqlite3 in production mode which results in a warning in
the test output. This change sets the config option for silencing this
warning so we don't see it in test output.

railties/test/application/loading_test.rb

@@ -418,6 +418,7 @@ def test_initialize_can_be_called_at_any_time
   end
 
   test "active record query cache hooks are installed before first request in production" do
+    add_to_config "config.active_record.sqlite3_production_warning = false"
     app_file "app/controllers/omg_controller.rb", <<-RUBY
       begin
         class OmgController < ActionController::Metal