message: Fix tensorflow master build failure with verbs
  This fix tries to address the issue in 21999 where
  tensorflow master build failed with verbs. The issue was caused
  by StringPiece replaced with `absl::string_view`
  This fix fixes 21999
diff: @@ -63,7 +63,7 @@ void RdmaRemoteRendezvous::RecvFromRemoteAsync(
  }
  CHECK(dst_name.compare(rdma_mgr_->local_worker()) == 0);
  RdmaChannel* rc = rdma_mgr_->FindChannel(src_name);
  - string key(std::move(parsed.FullKey().ToString()));
  + string key(parsed.FullKey());
  string key_with_step_id = VerbsUtil::AppendStepidToKey(key, step_id_);
  Device* dst_dev;
  