LFC logs are not under control of config
e.g. log pattern does not follow the one set for DHCP4:
2019-08-13 18:19:16.205 INFO [kea-dhcp4.dhcpsrv/25380] DHCPSRV_MEMFILE_LFC_START starting Lease File Cleanup
2019-08-13 18:19:16.206 INFO [kea-dhcp4.dhcpsrv/25380] DHCPSRV_MEMFILE_LFC_EXECUTE executing Lease File Cleanup using: /usr/sbin/kea-lfc -4
INFO [DhcpLFC] LFC_START Starting lease file cleanup
INFO [DhcpLFC] LFC_PROCESSING Previous file: /var/lib/kea/kea-leases4.csv.2, copy file: /var/lib/kea/kea-leases4.csv.1
INFO [DhcpLFC.dhcpsrv] DHCPSRV_MEMFILE_LEASE_FILE_LOAD loading leases from file /var/lib/kea/kea-leases4.csv.2
```