Use RegisterWithoutStarting in log_to_mcap

This prevents the LogReader from fast-forwarding to when everything
starts, which tends to exclude important messages from during boot.

Change-Id: I86fc6ee6467e00b5e2d2c071052caf7e19df9ef1
Signed-off-by: James Kuszmaul <james.kuszmaul@bluerivertech.com>
diff --git a/aos/util/log_to_mcap.cc b/aos/util/log_to_mcap.cc
index e669658..ca2c98d 100644
--- a/aos/util/log_to_mcap.cc
+++ b/aos/util/log_to_mcap.cc
@@ -41,8 +41,8 @@
   }
 
   aos::logger::LogReader reader(logfiles);
-
-  reader.Register();
+  aos::SimulatedEventLoopFactory factory(reader.configuration());
+  reader.RegisterWithoutStarting(&factory);
 
   const aos::Node *node =
       (replay_node.empty() ||
@@ -63,4 +63,5 @@
       FLAGS_compress ? aos::McapLogger::Compression::kLz4
                      : aos::McapLogger::Compression::kNone);
   reader.event_loop_factory()->Run();
+  reader.Deregister();
 }