added option tcpka to HAProxy conf file

Author: Soufiane Benali

haproxy.cfg

@@ -19,6 +19,7 @@ listen stats
 listen galera
   bind 0.0.0.0:3306
   mode tcp
+  option tcpka
   option mysql-check
   server mysql-1 ${DB1_ADDRESS}:${DB1_PORT} check
   server mysql-2 ${DB3_ADDRESS}:${DB2_PORT} check backup