software/kvm: Drop obsoleted nbd functionality

6 jobs for master
Status Job ID Name Coverage
  External
passed Cloudooo.UnitTest-Master

00:15:47

passed SlapOS.Eggs.UnitTest-Master.Python2

00:24:06

passed SlapOS.Eggs.UnitTest-Master.Python3

00:28:08

passed SlapOS.Eggs.UnitTest-Master.Python3Next

00:39:34

running SlapOS.SoftwareReleases.IntegrationTest-Master

967:12:31

passed SlapOS.Theia.ResilienceTest-Master-ERP5

11:54:38