enable etcd logging in local-e2e jobs

We are not saving the etcd logs and just redirecting the output
to /dev/null. In this change, we set ETCD_LOGFILE to the same
directory where we log other kube relates processes.

Change-Id: I719a941665b749b864f2efdcdfc7ddc7b2a61776

hack/local-up-cluster.sh

@@ -445,6 +445,7 @@ function warning_log {
 
 function start_etcd {
     echo "Starting etcd"
+    ETCD_LOGFILE=${LOG_DIR}/etcd.log
     kube::etcd::start
 }