fix scheduling issue with logrotate monthly scrapes #123
Description
currently, the logrotate runs on the first of the month to rotate the log file from the scrape. However, the scrape runs on the last day of the month & takes multiple days. Because there is a process with a write lock on the log file, this means that it does not rotate correctly first time, which leads it to do a messy rotation the next time. I've just tidied up some of the unnecessary empty log files (& added config to logrotate to not rotate empty files), but some further tweaks would be nice to tidy things up a bit more.