Add final assertion

To make sure that the domain is in the right state after out-of-order
execution of the lock removal

test/system/admin_area/domains/registry_lock_test.rb

@@ -51,5 +51,6 @@ class RegistryLockTest < JavaScriptApplicationSystemTestCase
     end
 
     assert_text('Registry lock could not be removed')
+    refute @domain.locked_by_registrant?
   end
 end