chore: reduce timeout intervals

It improves reconnectiblity in the case of server restarts where all connected
clients are kicked out and expected to reconnect in a timely manner.

template/client.ovpn.tmpl

@@ -9,7 +9,7 @@ resolv-retry infinite
 ns-cert-type server
 cipher AES-128-CBC
 nobind
-keepalive 2 20
+keepalive 2 4
 persist-key
 persist-tun
 comp-lzo

template/server.conf.tmpl

@@ -213,7 +213,7 @@ client-to-client
 # peer is down if no ping received during
 # a 120 second time period.
 ;keepalive 10 120
-keepalive 2 20
+keepalive 2 4
 
 # For extra security beyond that provided
 # by SSL/TLS, create an "HMAC firewall"