Remove aliases with two letter:

There a issues is use more than one character to use as aliases
https://github.com/erikhuda/thor/blob/a5cbed8/lib/thor/base.rb#L307

So, for this change the convention is remove the two letters aliases
rails#38813

Author: roramirez

railties/lib/rails/generators.rb

@@ -34,12 +34,9 @@ module Generators
         actions: "-a",
         orm: "-o",
         javascripts: "-j",
-        javascript_engine: "-je",
         resource_controller: "-c",
         scaffold_controller: "-c",
         stylesheets: "-y",
-        stylesheet_engine: "-se",
-        scaffold_stylesheet: "-ss",
         template_engine: "-e",
         test_framework: "-t"
       },