Unify and standardize inventory_hostname

This was causing some confusing conflicts, so create a new fact called
"this_node" which is inventory_hostname.split('.')[0], i.e. the short
name, and use that everywhere instead of an FQDN or true inventory
hostname.

roles/pvc/templates/libvirt/libvirtd.conf.j2

@@ -3,6 +3,6 @@
 
 listen_tls = 0
 listen_tcp = 1
-listen_addr = "{% for node in pvc_nodes if node.hostname == inventory_hostname %}{{ node.cluster_ip }}{% endfor %}"
+listen_addr = "{% for node in pvc_nodes if node.hostname == this_node %}{{ node.cluster_ip }}{% endfor %}"
 tcp_port = "16509"
 auth_tcp = "none"