Revert "Ensure config.active_record.time_zone_aware_types is always set"

This reverts commit 43ccebc.

This is not fixing the configuration problem since we are assigning to
the ActiveRecord::Base not the configuration. See rails#24303.

Author: rafaelfranca

activerecord/lib/active_record/railtie.rb

@@ -65,7 +65,6 @@ class Railtie < Rails::Railtie # :nodoc:
       ActiveSupport.on_load(:active_record) do
         self.time_zone_aware_attributes = true
         self.default_timezone = :utc
-        self.time_zone_aware_types = ActiveRecord::Base.time_zone_aware_types
       end
     end