Set new user and hostname of nfsroot
tested in playground https://lava.collabora.co.uk/scheduler/job/1638292
see also https://gitlab.apertis.org/infrastructure/apertis-tests/merge_requests/123
tested in playground https://lava.collabora.co.uk/scheduler/job/1638292
see also https://gitlab.apertis.org/infrastructure/apertis-tests/merge_requests/123