enable hairpin by default (#568)

Author: tamilmani1989

cni/azure-linux.conflist

@@ -6,7 +6,6 @@
          "type":"azure-vnet",
          "mode":"bridge",
          "bridge":"azure0",
-         "disableHairpinOnHostInterface":true,
          "ipsToRouteViaHost":["169.254.20.10"],
          "ipam":{
             "type":"azure-vnet-ipam"