Maintenance jobs logging improvements

[sumerman]

The idea here is to redirect maintenance jobs logs into a (hyper)table while bypassing the transaction control using the mechanism built for #495. Alternatively, and at the very least, logging levels should be separated in a way that would make each job output once per run with a default configuration, with the possibility to configure more detailed logging. And the log lines should bear a distinct prefix.

Either way, the aim here is to separate the maintenance job logs from the rest of the database logs, making them easy to get to and search through.