T6228: Cleanup of not existing systemd units

Delete not existing units:
```
06:12:51  Failed to disable unit, unit logd.service does not exist.
06:12:51  Failed to disable unit, unit heartbeat.service does not exist.
```

data/live-build-config/hooks/live/18-enable-disable_services.chroot

@@ -21,15 +21,13 @@ systemctl disable conntrackd.service
 systemctl disable 'udp-broadcast-relay@*.service'
 systemctl disable pdns-recursor.service
 systemctl disable tftpd-hpa.service
-systemctl disable logd.service
 systemctl disable frr.service
 systemctl disable salt-minion.service
 systemctl disable certbot.service
 systemctl disable certbot.timer
 systemctl disable nginx.service
 systemctl disable wpa_supplicant.service
 systemctl disable squid.service
-systemctl disable heartbeat.service
 systemctl disable apt-daily.service
 systemctl disable apt-daily.timer
 systemctl disable apt-daily-upgrade.timer