Switch LogReader::Nodes to LoggedNodes

If folks want a list of nodes from the simulated config, they should
instead use the factory configuration.  Most of the time, we want to
instead use the nodes from the logged configuration.  Flip everything
over.

We should probably consider removing the helper since it doesn't really
add much.

Change-Id: I8f2150df9c50acfc0d7444f42b37820516fe072f
diff --git a/aos/events/logging/log_stats.cc b/aos/events/logging/log_stats.cc
index 47f3c5c..7d8f1f1 100644
--- a/aos/events/logging/log_stats.cc
+++ b/aos/events/logging/log_stats.cc
@@ -83,7 +83,7 @@
   if (aos::configuration::MultiNode(reader.configuration())) {
     if (FLAGS_node.empty()) {
       LOG(INFO) << "Need a --node specified.  The log file has:";
-      for (const aos::Node *node : reader.Nodes()) {
+      for (const aos::Node *node : reader.LoggedNodes()) {
         LOG(INFO) << "  " << node->name()->string_view();
       }
       return 1;