message: [tf.data] Rename RebatchDatasetV1 name label from Rebatch to LegacyRebatch.
diff: @@ -27,7 +27,8 @@ inline int64 CeilDiv(int64 dividend, int64 divisor) {
  return (dividend - 1 + divisor) / divisor;
  }
  -constexpr const char* const kDatasetType = "Rebatch";
  +constexpr const char* const kDatasetTypeV1 = "Rebatch";
  +constexpr const char* const kDatasetTypeV2 = "RebatchV2";
  class RebatchDatasetOp : public UnaryDatasetOpKernel {
  public:
  @@ -73,7 +74,7 @@ class RebatchDatasetOp : public UnaryDatasetOpKernel {
  const string& prefix) const override {
  name_utils::IteratorPrefixParams params;
  return absl::make_unique<Iterator>(Iterator::Params{
  - this, name_utils::IteratorPrefix(kDatasetType, prefix, params)});
  + this, name_utils::IteratorPrefix(kDatasetTypeV1, prefix, params)});
  }
  const DataTypeVector& output_dtypes() const override {
  @@ -87,7 +88,7 @@ class RebatchDatasetOp : public UnaryDatasetOpKernel {
  string DebugString() const override {
  name_utils::DatasetDebugStringParams params;
  params.set_args(num_replicas_);
  - return name_utils::DatasetDebugString(kDatasetType, params);
  + return name_utils::DatasetDebugString(kDatasetTypeV1, params);
  }
  Status CheckExternalState() const override {
  @@ -330,7 +331,7 @@ class RebatchDatasetV2Op : public UnaryDatasetOpKernel {
  const string& prefix) const override {
  name_utils::IteratorPrefixParams params;
  return absl::make_unique<Iterator>(Iterator::Params{
  - this, name_utils::IteratorPrefix(kDatasetType, prefix, params)});
  + this, name_utils::IteratorPrefix(kDatasetTypeV2, prefix, params)});
  }
  const DataTypeVector& output_dtypes() const override {
  @@ -342,7 +343,7 @@ class RebatchDatasetV2Op : public UnaryDatasetOpKernel {
  }
  string DebugString() const override {
  - return name_utils::DatasetDebugString(kDatasetType);
  + return name_utils::DatasetDebugString(kDatasetTypeV2);
  }
  Status CheckExternalState() const override {
  