use the new clear_validators! api everywhere to reset validators in tests

activemodel/test/cases/validations/acceptance_validation_test.rb

@@ -63,6 +63,6 @@ class AcceptanceValidationTest < ActiveModel::TestCase
     p.karma = "1"
     assert p.valid?
   ensure
-    Person.reset_callbacks(:validate)
+    Person.clear_validators!
   end
 end

activerecord/test/cases/persistence_test.rb

@@ -740,7 +740,7 @@ class PersistenceTest < ActiveRecord::TestCase
 
     assert_raise(ActiveRecord::RecordInvalid) { reply.update!(title: nil, content: "Have a nice evening") }
   ensure
-    Reply.reset_callbacks(:validate)
+    Reply.clear_validators!
   end
 
   def test_update_attributes!
@@ -761,7 +761,7 @@ class PersistenceTest < ActiveRecord::TestCase
 
     assert_raise(ActiveRecord::RecordInvalid) { reply.update_attributes!(title: nil, content: "Have a nice evening") }
   ensure
-    Reply.reset_callbacks(:validate)
+    Reply.clear_validators!
   end
 
   def test_destroyed_returns_boolean

activerecord/test/cases/validations/i18n_generate_message_validation_test.rb

@@ -3,7 +3,7 @@ require 'models/topic'
 
 class I18nGenerateMessageValidationTest < ActiveRecord::TestCase
   def setup
-    Topic.reset_callbacks(:validate)
+    Topic.clear_validators!
     @topic = Topic.new
     I18n.backend = I18n::Backend::Simple.new
   end