worker nodes in kni-upi-lab should be named with short hostname

When adding master and worker nodes with knictl and kni-upi-lab, they get named differently:

NAME STATUS ROLES AGE VERSION
slave-master-0 Ready master 26h v1.17.1+1aa1c48
slave-master-1 Ready,SchedulingDisabled master 26h v1.17.1+1aa1c48
slave-master-2 Ready master 26h v1.17.1+1aa1c48
slave-worker-0.slave.baremetal.edge-sites.net Ready worker 26h v1.17.1+1aa1c48
slave-worker-1.slave.baremetal.edge-sites.net Ready worker 24h v1.17.1+1aa1c48

See that masters take short hostname, while workers take full FQDN.
Naming should be consistent across masters/workers, and we prefer to use the short hostname.