Revert "cheat to fix duplicate key on thumbnails"

This reverts commit 0c702522c4.

app/models/upload.rb

@@ -34,11 +34,6 @@ class Upload < ActiveRecord::Base
     return unless width > SiteSetting.auto_link_images_wider_than
     return if has_thumbnail?
     thumbnail = OptimizedImage.create_for(self, width, height)
-    # TODO: @regis we may want to do the more cleanly, create_for may change the dimensions
-    # this avoids a duplicate key, it should be done more cleanly, this is cheating
-    thumbnail.width = width
-    thumbnail.height = height
-
     optimized_images << thumbnail if thumbnail
   end