message: Fix up difference between v1 and v2
  Summary: Ref  T18690
  Test Plan: It compiles in v2
  Reviewers: #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, davidn
  Maniphest Tasks: T18690
diff: @@ -84,7 +84,7 @@ Status PipelineVerifier::VerifyGradientAccumulation(HloModule* module,
  // We expect the gradient accumulation creators to only be used by
  // backward pipeline stages residing on the same shard.
  for (HloInstruction* user : inst->users()) {
  - const std::vector<int64> indices = user->OperandIndices(inst);
  + const auto indices = user->OperandIndices(inst);
  if (indices.size() != 1) {
  return InternalErrorStrCat(
  "Expected the gradient accumulation buffer to only appear as an "
  @@ -124,8 +124,7 @@ Status PipelineVerifier::VerifyGradientAccumulation(HloModule* module,
  inner_user->user_count(), " users.");
  }
  HloInstruction* next_user = inner_user->users()[0];
  - const std::vector<int64> next_user_indices =
  - next_user->OperandIndices(inner_user);
  + const auto next_user_indices = next_user->OperandIndices(inner_user);
  if (next_user_indices.size() != 1) {
  return InternalErrorStrCat(
  