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_cat.cc b/aos/events/logging/log_cat.cc
index f9da914..c8407f1 100644
--- a/aos/events/logging/log_cat.cc
+++ b/aos/events/logging/log_cat.cc
@@ -147,7 +147,8 @@
 
   bool found_channel = false;
 
-  for (const aos::Node *node : reader.Nodes()) {
+  for (const aos::Node *node :
+       aos::configuration::GetNodes(event_loop_factory.configuration())) {
     std::unique_ptr<aos::EventLoop> printer_event_loop =
         event_loop_factory.MakeEventLoop("printer", node);
     printer_event_loop->SkipTimingReport();