Fix ansible-test pylint and pep8 issues. (#24245)

* Fix pylint useless-super-delegation issues.
* Fix miscellaneous pylint issues.
* Fix PEP 8 issues.
* Fix warnings reported by PyCharm.

test/runner/lib/executor.py

@@ -29,7 +29,6 @@ from lib.manage_ci import (
 )
 
 from lib.util import (
-    CommonConfig,
     EnvironmentConfig,
     ApplicationWarning,
     ApplicationError,
@@ -83,10 +82,6 @@ from lib.test import (
     TestSkipped,
 )
 
-from lib.metadata import (
-    Metadata,
-)
-
 SUPPORTED_PYTHON_VERSIONS = (
     '2.6',
     '2.7',
@@ -478,9 +473,9 @@ def command_integration_filtered(args, targets):
                 run_command(args, ['ssh', '-o', 'BatchMode=yes', 'localhost', 'id'], capture=True)
                 display.info('SSH service responded.')
                 break
-            except SubprocessError as ex:
+            except SubprocessError:
                 if i == max_tries:
-                    raise ex
+                    raise
                 seconds = 3
                 display.warning('SSH service not responding. Waiting %d second(s) before checking again.' % seconds)
                 time.sleep(seconds)