[hotfix][nodes] only use ASn in interface name

- it is only 15 chars by default (change requires kernel recompile)
- thanks to @famfo for have a long mntner name

nodes/templates/bgp-peer.template.conf

@@ -1,7 +1,7 @@
 {% if peering["bgp_mp"] %}
 protocol bgp dn42_{{peering["MNT"][:-4].lower()}}_{{peering["ASN"][-4:]}} from dnpeers {
   neighbor {{peering["ipv6ll"]}} as {{peering["ASN"]}};
-  interface "dn42_{{peering['MNT'][:-4].lower()}}_{{peering['ASN'][-4:]}}";
+  interface {% if peering['ASN'].__len__() >=6 %}"dn42_{{peering['ASN'][-6:]}}"{% else %}"dn42_{{peering['asn']}}"{% endif %};
   passive off;
 
   ipv4 {