Call load_schema before assert_no_queries

Follow up 45be690f8e.

`predicate_builder.build` in `where` requires `load_schema` for
`type_for_attribute`.

activerecord/test/cases/null_relation_test.rb

@@ -17,6 +17,7 @@ class NullRelationTest < ActiveRecord::TestCase
   end
 
   def test_none_chainable
+    Developer.send(:load_schema)
     assert_no_queries do
       assert_equal [], Developer.none.where(name: "David")
     end