Enable buffered logging for scripted dinit services

The current dinit implementation of `buffered` logging is pretty limited[1]: when the log size exceeds the maximum specified by `log-buffer-size`, the output is truncated, instead of rotating the buffer, i.e., FIFO. However, scripted services usually don't yield a lot of log, and thus could be (relatively) safe to use `buffered` output, this is definitely an improvement since we currently don't enable any type of logging for them. [1]: https://github.com/davmac314/dinit/issues/315