Rec: structured logging for periodic stats

[omoerbeek]

Short description

Also change the level to Info as that is the appropriate level: no action required. Notice is a level that might need action. The guidance in the OpenBSD man page is:

     LOG_EMERG     A panic condition.  This is normally broadcast to all
                   users.

     LOG_ALERT     A condition that should be corrected immediately, such as a
                   corrupted system database.

     LOG_CRIT      Critical conditions, e.g., hard device errors.

     LOG_ERR       Errors.

     LOG_WARNING   Warning messages.

     LOG_NOTICE    Conditions that are not error conditions, but should
                   possibly be handled specially.

     LOG_INFO      Informational messages.

     LOG_DEBUG     Messages that contain information normally of use only when
                   debugging a program.

IMO it would not hurt to review the syslog levels of the messages at some point, as we tend to use a non-adequate levels here and there.

Checklist

I have:

• read the CONTRIBUTING.md document
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)