Fix tempest and pep8 tests

Fix tempest jobs to properly use tempest-horizon as tempest-plugin in
job configuration.

Flake8 3.8.0 fixed a few bugs so that additional issues are marked, fix
these.

Co-Authored-By: Andreas Jaeger <aj@suse.com>
Change-Id: I2aca3286ea2cc1ade567087786781952489d6efa
(cherry picked from commit a0a85dd176)

.zuul.yaml

@@ -71,13 +71,14 @@
       - ^openstack_dashboard/dashboards/.*/tests.py$
     vars: &base_vars
       devstack_localrc:
-        TEMPEST_PLUGINS: "{{ ansible_user_dir }}/src/opendev.org/openstack/tempest-horizon"
         USE_PYTHON3: true
       devstack_services:
         horizon: true
         tempest: true
       tempest_concurrency: 2
       tempest_test_regex: horizon
+      tempest_plugins:
+        - tempest-horizon
       tox_envlist: all
 
 - job:

openstack_dashboard/api/cinder.py

@@ -127,6 +127,7 @@ class VolumeBackup(BaseCinderAPIResourceWrapper):
               'created_at', 'volume_id', 'availability_zone', 'snapshot_id']
     _volume = None
     _snapshot = None
+
     @property
     def volume(self):
         return self._volume

openstack_dashboard/settings.py

@@ -41,7 +41,7 @@ monkeypatch_escape()
 
 # Load default values
 # pylint: disable=wrong-import-position
-from openstack_dashboard.defaults import *  # noqa: F403,H303
+from openstack_dashboard.defaults import *  # noqa: E402,F403,H303
 
 _LOG = logging.getLogger(__name__)
 

openstack_dashboard/test/settings.py

@@ -27,7 +27,7 @@ from openstack_dashboard.utils import settings as settings_utils
 monkeypatch_escape()
 
 # Load default values
-from openstack_dashboard.defaults import *  # noqa: F403,H303
+from openstack_dashboard.defaults import *  # noqa: E402,F403,H303
 
 WEBROOT = '/'