Move resetState from FieldValue to LogEvent

This helps save memory because FieldValues are copied around much more
than LogEvents.

+ removed unused variables from LogEvent

Test: bit statsd_test:*
Bug: 154267590
Change-Id: If444ef79c85a45526fce183b67d9d8a2e74fa10d
diff --git a/cmds/statsd/tests/LogEvent_test.cpp b/cmds/statsd/tests/LogEvent_test.cpp
index bb4578d..e52e2d0 100644
--- a/cmds/statsd/tests/LogEvent_test.cpp
+++ b/cmds/statsd/tests/LogEvent_test.cpp
@@ -352,7 +352,7 @@
 
     const vector<FieldValue>& values = event.getValues();
     EXPECT_EQ(values.size(), 1);
-    EXPECT_EQ(values[0].mAnnotations.getResetState(), resetState);
+    EXPECT_EQ(event.getResetState(), resetState);
 }
 
 }  // namespace statsd