Minor/cosmetic: Monitor logs time differently than the other pipeline stages

All pipeline stages, except for the monitor, use the logger with the formatter as configured in `config/logger.conf`. The monitor uses custom print instructions instead, with a different date-time string. I understand the reason might be that it's not trivial to configure the logging formatter to output a date string containing both fractional seconds and timezone, but it would be nice to have all pipeline stages showing the same time format.

Low priority issue.