Remove obsolete routes for poll questions

The routes for poll questions were accidentally deleted in commit
5bb831e959 when deleting the `:show` action, and restored in commit
9871503c5e. However, the deleted code was:

```
resources :questions, only: [:show], controller: 'polls/questions' (...)
```

While the restored code was:

```
resources :questions, controller: 'polls/questions' (...)
```

Meaning we forgot to add the `only: []` option when restoring the
routes.

We also forgot to remove the `before_action` code when deleting the
`:show` action, so we're removing it now.

app/controllers/polls/questions_controller.rb

@@ -2,8 +2,6 @@ class Polls::QuestionsController < ApplicationController
   load_and_authorize_resource :poll
   load_and_authorize_resource :question, class: "Poll::Question"
 
-  has_orders %w[most_voted newest oldest], only: :show
-
   def answer
     answer = @question.find_or_initialize_user_answer(current_user, params[:answer])
     answer.save_and_record_voter_participation

config/routes/poll.rb

@@ -4,7 +4,7 @@ resources :polls, only: [:show, :index] do
     get :results
   end
 
-  resources :questions, controller: "polls/questions", shallow: true do
+  resources :questions, controller: "polls/questions", shallow: true, only: [] do
     post :answer, on: :member
     resources :answers, controller: "polls/answers", only: :destroy, shallow: false
   end

spec/routing/polymorphic_routes_spec.rb

@@ -53,12 +53,6 @@ describe "Polymorphic routes" do
       )
     end
 
-    it "routes poll questions" do
-      question = create(:poll_question)
-
-      expect(polymorphic_path(question)).to eq question_path(question)
-    end
-
     it "routes topics" do
       community = create(:proposal).community
       topic = create(:topic, community: community)