DEV: Add test-site-settings to asset pipeline (#18935)

Follow up to 59da6c6ea2

config/initializers/assets.rb

@@ -28,6 +28,7 @@ Rails.application.config.assets.precompile += %w{
   wizard.js
   test-support.js
   test-helpers.js
+  test-site-settings.js
   browser-detect.js
   browser-update.js
   break_string.js

spec/requests/qunit_controller_spec.rb

@@ -98,6 +98,7 @@ RSpec.describe QunitController do
         expect(response.body).to include("/assets/locales/en.js")
         expect(response.body).to include("/test-support")
         expect(response.body).to include("/test-helpers")
+        expect(response.body).to include("/test-site-settings")
         expect(response.body).to include("/assets/markdown-it-bundle.js")
         expect(response.body).to include("/assets/discourse.js")
         expect(response.body).to include("/assets/admin.js")