Handle new user and hostname of nfsroot

The nfsroot nfsuser has been renamed user. The nfsroot apertis-nfs machine name changed to apertis. Only the group-nfs-tpl.yaml test changed because other tests are still using a 18.09 release. When we update lava, it will be time to update other tests.

Signed-off-by: Frédéric Dalleau frederic.dalleau@collabora.com

tested in playground https://lava.collabora.co.uk/scheduler/job/1638292