Change count metrics to report absolute instead of cumulative value

Author: cgilmour

src/datadog/metrics.cpp

@@ -12,7 +12,7 @@ const std::string Metric::name() { return name_; }
 const std::string Metric::type() { return type_; }
 const std::vector<std::string> Metric::tags() { return tags_; }
 bool Metric::common() { return common_; }
-uint64_t Metric::value() { return value_; }
+uint64_t Metric::value() { return value_.exchange(0); }
 
 CounterMetric::CounterMetric(const std::string name,
                              const std::vector<std::string> tags, bool common)

src/datadog/tracer_telemetry.cpp

@@ -100,9 +100,6 @@ void TracerTelemetry::capture_metrics() {
                          .count();
   for (auto& m : metrics_snapshots_) {
     auto value = m.first.get().value();
-    if (value == 0) {
-      continue;
-    }
     m.second.emplace_back(timepoint, value);
   }
 }