* Replace all `rlog` occurrences with the shared logger

* Use the same log format in `InitLoggerStderrOnly` as well

* Convert one more `log.Fatal` to `logger.Log.Errorf` as well in the `cli`

* Replace `log.` occurrences with `logger.Log.` in `agent`

* Fix `cannot use err (type error)`

* Change the logging level to `DEBUG`

* Replace an `Errorf` with `Fatal`

* Add informative message