Since we set 'eth0' as default NIC name, we get following error when running scylla_setup in non-interactive mode without --nic parameter:
$ sudo scylla_setup --setup-nic-and-disks --no-raid-setup --no-verify-package --no-io-setup
NIC eth0 doesn't exist.
It looks strange since user actually does not specified 'eth0', they might forget to specify --nic.
I think we should shows up usage, when eth0 is not available on the system.
Fixes#5828