server: Use default logging configuration instead of zap production one

This fixes problem where logs json changes format of timestamp.

server/etcdmain/main.go

@@ -41,9 +41,6 @@ func Main(args []string) {
 }
 
 func notifySystemd(lg *zap.Logger) {
-	if lg == nil {
-		lg = zap.NewExample()
-	}
 	lg.Info("notifying init daemon")
 	_, err := daemon.SdNotify(false, daemon.SdNotifyReady)
 	if err != nil {