Test formatting errors with log level being emitted

The test to ensure that formatting errors are handled properly was being
run using info level logging, but the default log configuration for
tests does not emit messages at that level, so switch to error.

Back-ported from commit with the same ID in oslo.log.

Change-Id: Ie11a51deea65627b45a11d7dfca36d16c1b5949e

tests/unit/fixture/test_logging.py

@@ -23,6 +23,6 @@ def test_logging_handle_error(self):
         LOG.info('pid of first child is %(foo)s', 1)
         self.useFixture(logging_fixture.get_logging_handle_error_fixture())
         self.assertRaises(TypeError,
-                          LOG.info,
+                          LOG.error,
                           'pid of first child is %(foo)s',
                           1)