In the DBs configurations we don't set the log_error and slow_query_log_file variables so the default values are used and the files are saved in the data directory and we don't configure a custom logrotate.
Although the slow_query_log is OFF by default and the error log is usually small, in some servers we have it quite big, particularly on masters:
-rw-r----- 1 mysql root 12G Feb 21 09:53 db1052.err -rw-r----- 1 mysql root 27G Feb 21 10:11 db1038.err
I think we should configure some logrotation policy.