Code review comment for ~raychan96/charm-telegraf:update-test-bundle

This was a silence error, and I also could not find out when and how telegraf was changed from the upstream project. However, this is a new bug because both `install_method=deb` and `install_method=snap` reported the same issue in the `journalctl -u telegraf` and `snap logs telegraf` making the config `logfile` practically unusable because it always redirect to stderr, hence `/var/log/telegraf/telegraf.log` does not exists and also `test_04_plugin_errors` failed with "No such file or directory"