Handling high freq in batches

[malish8632]

Since PubSubPluginSync.sendBatches() uses exactly the same line added here we could use .sendMetrics() and detect high frequency metrics.

public AsyncFuture<Void> sendBatches(Collection<Batch> batches) { final List<Metric> metrics = BatchMetricConverter.convertBatchesToMetrics(batches); return sendMetrics(metrics); }