Generate domain-name unique names in genEmptyCluster
Generate domain-name unique names in genEmptyCluster

It is a prerequisite that all nodes in a cluster have different names.
In genEmptyCluster, this is achieved by adding a unique suffix to each
name. However, this still allows to have both, 'n-3' and 'n-3.n-4' as
names in the same cluster---and those names are considered equal, as
they might both the legitimate short hands of 'n-3.n-4.example.com'.

To avoid these kinds of name collisions, make genEmptyCluster only
use the first part of the FQDN and suffix it.

Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Helga Velroyen <2d0126b1ec6f9ec5cbec4a7012aa14faeaef10f5@google.com>

ganeti/ganeti,dimara/ganeti,andir/ganeti,apyrgio/ganeti,grnet/snf-ganeti,apyrgio/ganeti,andir/ganeti,yiannist/ganeti,mbakke/ganeti,bitemyapp/ganeti,ganeti/ganeti,leshchevds/ganeti,leshchevds/ganeti,grnet/snf-ganeti,yiannist/ganeti,bitemyapp/ganeti,mbakke/ganeti,ganeti/ganeti,mbakke/ganeti,dimara/ganeti,yiannist/ganeti,leshchevds/ganeti,onponomarev/ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,onponomarev/ganeti,ganeti-github-testing/ganeti-test-1