test: Add test for http.route cleaning

Author: akahn

instrumentation/action_pack/test/opentelemetry/instrumentation/action_pack/handlers/action_controller_test.rb

@@ -58,6 +58,12 @@
     _(span.attributes['code.function']).must_equal 'ok'
   end
 
+  it 'strips (:format) from http.route' do
+    get 'items/1234'
+
+    _(span.attributes['http.route']).must_equal '/items/:id'
+  end
+
   it 'does not memoize data across requests' do
     get '/ok'
     get '/items/new'