etcd.conf.yml: use "stderr" for log-outputs
Fix "TestEtcdExampleConfig".
@@ -131,7 +131,7 @@ debug: false
logger: zap
# Specify 'stdout' or 'stderr' to skip journald logging even when running under systemd.
-log-outputs: [default]
+log-outputs: [stderr]
# Force to create a new one member cluster.
force-new-cluster: false
