Cleanup unused systemd files.

contrib/cc-slurm-sync.service

-[Unit]
-Description=Sync slurm with ClusterCockpit
-
-[Service]
-Type=oneshot
-WorkingDirectory=/opt/software/slurm/cc-slurm-sync
-ExecStart=/opt/software/slurm/cc-slurm-sync/slurm-clusercockpit-sync.py
-User=root
-
-[Install]
-WantedBy=multi-user.target

contrib/cc-slurm-sync.timer

-[Unit]
-Description=Sync slurm with ClusterCockpit timer
-
-[Timer]
-OnCalendar=*-*-* *:*:00
-Persistent=false
-
-[Install]
-WantedBy=timers.target