Replace oslo_utils.encodeutils.exception_to_unicode

The function is being deprecated now because it is equivalent to
str(ex) in Python 3.

Depends-on: https://review.opendev.org/c/openstack/oslo.utils/+/938929
Change-Id: I2242f9f8ca92b5c9371725b1bbe54f13a0652144

ceilometer/publisher/messaging.py

@@ -23,7 +23,6 @@ import threading
 from oslo_config import cfg
 from oslo_log import log
 import oslo_messaging
-from oslo_utils import encodeutils
 from oslo_utils import excutils
 from urllib import parse as urlparse
 
@@ -64,9 +63,7 @@ class DeliveryFailure(Exception):
 
 
 def raise_delivery_failure(exc):
-    excutils.raise_with_cause(DeliveryFailure,
-                              encodeutils.exception_to_unicode(exc),
-                              cause=exc)
+    excutils.raise_with_cause(DeliveryFailure, str(exc), cause=exc)
 
 
 class MessagingPublisher(publisher.ConfigPublisherBase, metaclass=abc.ABCMeta):

ceilometer/tests/unit/meter/test_notifications.py

@@ -17,7 +17,6 @@ from unittest import mock
 import fixtures
 from oslo_cache import core as cache
 from oslo_config import fixture as config_fixture
-from oslo_utils import encodeutils
 from oslo_utils import fileutils
 import yaml
 
@@ -267,7 +266,7 @@ class TestMeterDefinition(test.BaseTestCase):
             self.assertIn("Required fields ['name', 'type', 'event_type',"
                           " 'unit', 'volume', 'resource_id']"
                           " not specified",
-                          encodeutils.exception_to_unicode(e))
+                          str(e))
 
     def test_bad_type_cfg_definition(self):
         cfg = dict(name="test", type="foo", event_type="bar.create",
@@ -277,8 +276,7 @@ class TestMeterDefinition(test.BaseTestCase):
         try:
             notifications.MeterDefinition(cfg, conf, mock.Mock())
         except declarative.DefinitionException as e:
-            self.assertIn("Invalid type foo specified",
-                          encodeutils.exception_to_unicode(e))
+            self.assertIn("Invalid type foo specified", str(e))
 
 
 class CacheConfFixture(config_fixture.Config):