Revert "Merge pull request rails#53330 from Shopify/active-model-dirty-skip-reset"

This reverts commit 0586c88, reversing
changes made to 92410a1.

Author: byroot

activemodel/lib/active_model/dirty.rb

@@ -252,7 +252,7 @@ def initialize_dup(other) # :nodoc:
 
     def init_attributes(other) # :nodoc:
       attrs = super
-      if other.persisted? && self.class.respond_to?(:_default_attributes)
+      if self.class.respond_to?(:_default_attributes)
         self.class._default_attributes.map do |attr|
           attr.with_value_from_user(attrs.fetch_value(attr.name))
         end