message: [tf.data service] Rename GetElement TraceMe to GetDataServiceElement
  This makes it clearer what the TraceMe means when it shows up in xprof traces.
diff: @@ -448,7 +448,7 @@ class DataServiceDatasetOp::Dataset : public DatasetBase {
  TF_LOCKS_EXCLUDED(mu_) {
  VLOG(3) << "Getting an element for task id " << task->task_id;
  tensorflow::profiler::TraceMe activity(
  - "GetElement", tensorflow::profiler::TraceMeLevel::kInfo);
  + "GetDataServiceElement", tensorflow::profiler::TraceMeLevel::kInfo);
  CompressedElement compressed;
  bool end_of_sequence;
  for (int num_retries = 0;; ++num_retries) {
  