Replace occurences of alias_method_chain with their Module#prepend counterpart

There is still one [here](https://github.com/rails/rails/blob/master/activesupport/lib/active_support/core_ext/object/json.rb#L41) and [there](https://github.com/rails/rails/blob/master/activesupport/lib/active_support/deprecation/method_wrappers.rb#L34) where I could not find a working replacement with passing tests.

The advantages are quite minor but I believe it is still an improvement.