Apply suggestions from code review

Author: dmehala

src/datadog/datadog_agent.cpp

@@ -232,9 +232,9 @@ void DatadogAgent::flush() {
   auto end = std::chrono::steady_clock::now();
 
   telemetry::distribution::add(
-      metrics::tracer::trace_chunk_size_ms,
+      metrics::tracer:: trace_chunk_serialization_duration,
       std::chrono::duration_cast<std::chrono::microseconds>(end - beg).count());
-  telemetry::distribution::add(metrics::tracer::trace_chunk_size_bytes,
+  telemetry::distribution::add(metrics::tracer:: trace_chunk_serialized_bytes,
                                static_cast<uint64_t>(body.size()));
 
   if (auto* error = encode_result.if_error()) {

src/datadog/telemetry_metrics.h

@@ -27,10 +27,10 @@ extern const telemetry::Counter spans_finished;
 extern const telemetry::Distribution trace_chunk_size;
 
 /// The size in bytes of the serialized trace chunk.
-extern const telemetry::Distribution trace_chunk_size_bytes;
+extern const telemetry::Distribution trace_chunk_serialized_bytes;
 
 /// The time it takes to serialize a trace chunk.
-extern const telemetry::Distribution trace_chunk_size_ms;
+extern const telemetry::Distribution trace_chunk_serialization_duration;
 
 /// The number of times a trace chunk is enqueued for sampling/serialization. In
 /// partial-flush scenarios, multiple trace chunks may be enqueued per trace