Miscellaneous pylint fixes.

The following rules are no longer disabled:

- bad-format-string
- duplicate-key
- lost-exception
- trailing-newlines
- unexpected-keyword-arg
- useless-suppression
- using-constant-test

test/units/modules/system/interfaces_file/test_interfaces_file.py

@@ -33,7 +33,6 @@ class AnsibleFailJson(Exception):
 class ModuleMocked():
     def fail_json(self, msg):
         raise AnsibleFailJson(msg)
-        pass
 
 
 module = ModuleMocked()