Revert "Merge pull request #33234 from alpaca-tc/autoload_activejob_arguments"

It breaks Active Job when run in isolation. E.g. bin/test test/cases/logging_test.rb:
https://travis-ci.org/rails/rails/jobs/398779028

Consider Rafaels suggestion of reviewing the eager loading instead:
https://github.com/rails/rails/pull/33234#issuecomment-401027419

This reverts commit cb0fdaacb2, reversing
changes made to a0a1abb3c7.

activejob/lib/active_job.rb

@@ -31,7 +31,6 @@ require "global_id"
 module ActiveJob
   extend ActiveSupport::Autoload
 
-  autoload :Arguments
   autoload :Base
   autoload :QueueAdapters
   autoload :Serializers

activejob/lib/active_job/enqueuing.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "active_job/arguments"
+
 module ActiveJob
   # Provides behavior for enqueuing jobs.
   module Enqueuing

activejob/lib/active_job/execution.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "active_support/rescuable"
+require "active_job/arguments"
 
 module ActiveJob
   module Execution