qa_crowbarsetup: Support cinder volume type select

Add 2 more variables to support cinder volume type selection.
$cinder_conf_volume_type indicates the type (e.g. local or netapp) and
$cinder_conf_volume_params can contain some configuration
parameters. E.g. to configure netapp, the variable could look like this:

storage_family 'ontap_7mode'
storage_protocol 'iscsi'
nfs_shares ''
vserver ''
netapp_server_hostname '192.168.124.11'
netapp_server_port 443
netapp_login 'admin'
netapp_password ''
netapp_vfiler ''
netapp_transport_type 'https'
netapp_volume_list ''
mkcloud: Also undefine virsh net and nodes

Networks and nodes are no longer transient so both must be undefined.