Ruby: Account for filter skip ordering

A `skip_*_filter :foo` call only has an effect if there was an earlier
call that registered `:foo` as a filter.

ruby/ql/test/library-tests/frameworks/action_controller/controllers/posts_controller.rb

@@ -6,6 +6,8 @@ class PostsController < ApplicationController
   # these calls override the earlier ones
   after_action :log_upvote, only: :upvote
   before_action :set_user
+  skip_before_action :set_user
+  before_action :set_user
 
   def index
   end