TST: Cleaned up test references to adjustments db

If we don't clean them up, then windows can delete
the temp dir with the db.

tests/test_benchmark.py

@@ -100,6 +100,7 @@ class TestBenchmark(TestCase):
 
     @classmethod
     def tearDownClass(cls):
+        del cls.data_portal
         del cls.env
         cls.tempdir.cleanup()