Move login_as after creating data for a test

It doesn't really affect the tests, but it helps isolate useless
assignments, and we already did it this way 94% of the time.

spec/features/budget_polls/polls_spec.rb

@@ -19,11 +19,10 @@ describe "Polls" do
   context "Admin index" do
 
     scenario "Budget polls should not appear in the list" do
-      login_as(create(:administrator).user)
-
       poll = create(:poll)
       budget_poll = create(:poll, :for_budget)
 
+      login_as(create(:administrator).user)
       visit admin_polls_path
 
       expect(page).to have_content(poll.name)