Add ForceDefaults to logfile_utils_test

When running without ForceDefaults, the test was failing.

Change-Id: I2dd9b358dccd42dc864bca56cc05b80ece38c873
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/aos/events/logging/logfile_utils_test.cc b/aos/events/logging/logfile_utils_test.cc
index e1e2ebd..9be70c6 100644
--- a/aos/events/logging/logfile_utils_test.cc
+++ b/aos/events/logging/logfile_utils_test.cc
@@ -479,6 +479,7 @@
     ++queue_index_[channel_index];
 
     flatbuffers::FlatBufferBuilder fbb;
+    fbb.ForceDefaults(true);
     fbb.FinishSizePrefixed(
         PackMessage(&fbb, context, channel_index, LogType::kLogMessage));