chore: fix python lint warnings (#14638)

* chore: fix lint warnings

* chore: another try at python import errors

Looks like the problem is that dbus_mock.py is running as
a script but living in the `lib/` directory where it's part of a
module. Moving it up into the `script/` directory seems to
solve the issue.

script/upload.py

@@ -210,5 +210,4 @@ def get_release(version):
   return release
 
 if __name__ == '__main__':
-  import sys
   sys.exit(main())