Fix flaky build

These tests have `use_transcational_tests` set to false so we need to
delete the `Cpk::Book` and `Cpk::Order` in the teardown to avoid flaky
builds.

Author: eileencodes

activerecord/test/cases/autosave_association_test.rb

@@ -939,6 +939,8 @@ class TestDestroyAsPartOfAutosaveAssociation < ActiveRecord::TestCase
     Parrot.delete_all
     @ship.delete
     @pirate.delete
+    Cpk::Book.delete_all
+    Cpk::Order.delete_all
   end
 
   # reload