core: remove unused variable from Message builtin

lib/vagrant/action/builtin/message.rb

@@ -4,9 +4,8 @@ module Vagrant
       # This middleware simply outputs a message to the UI.
       class Message
         def initialize(app, env, message, **opts)
-          @app    = app
+          @app     = app
-          @logger = Log4r::Logger.new("vagrant::action::builtin::is_state")
+          @message = message
-          @message  = message
         end
 
         def call(env)