I had troubles with pmm-agent filling up syslog with info message so I added a custom rsyslog config for it to discard the info messages. You could do the same or redirect the messages to a different path if wanted. Below is for pmm-agent, but can be adapted to pmm-admin or other program.
cat /etc/rsyslog.d/pmm-agent.config
if $programname == 'pmm-agent' and $syslogseverity-text == 'info' then stop