message: Fix recomp test
  Summary:
  This test was referring to instructions which are no longer there.
  Ref T17915
  Reviewers: #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, jakeh
  Maniphest Tasks: T17915
diff: @@ -382,18 +382,30 @@ TEST_F(NormInputRecomputationTest, RecomputeRelu) {
  EXPECT_TRUE(module_or_status.ok());
  auto* module = module_or_status.ValueOrDie().get();
  - HloInstruction* input1 = FindInstruction(module, "convolution.11");
  - HloInstruction* bn1 = FindInstruction(module, "batch-norm-training.13");
  - HloInstruction* bn_grad1 = FindInstruction(module, "batch-norm-grad.76");
  - HloInstruction* relu1 = FindInstruction(module, "relu.1");
  + CompilerAnnotations annotations(module);
  + ModuleFlatten flatten(annotations);
  + ConvolutionClassifier classifier(annotations);
  + CustomOpReplacer replacer{};
  + auto replacer_res = replacer.Run(module);
  +
  + EXPECT_TRUE(replacer_res.ok());
  + EXPECT_TRUE(replacer_res.ValueOrDie());
  +
  + HloInstruction* input1 = FindInstruction(module, "convolution.11");
  HloInstruction* input2 = FindInstruction(module, "convolution.23");
  +
  + HloInstruction* bn1 = FindInstruction(module, "batch-norm-training.13");
  HloInstruction* bn2 = FindInstruction(module, "batch-norm-training.25");
  +
  + HloInstruction* bn_grad1 = FindInstruction(module, "batch-norm-grad.76");
  HloInstruction* bn_grad2 = FindInstruction(module, "batch-norm-grad.50");
  - HloInstruction* relu_grad2 = FindInstruction(module, "relugrad.2");
  - std::cout << "RELU: " << relu1 << " grad " << relu_grad2 << " in " << input1
  - << "\n";
  + HloInstruction* relu1 = input2->mutable_operand(0);
  + EXPECT_TRUE(IsPoplarInstruction(PoplarOp::Relu)(relu1));
  +
  + HloInstruction* relu_grad2 = bn_grad1->mutable_operand(4);
  + EXPECT_TRUE(IsPoplarInstruction(PoplarOp::ReluGrad)(relu_grad2));
  ASSERT_EQ(input1->users().size(), 2);
  ASSERT_EQ(bn1->operand(0), input1);
  @@ -405,16 +417,6 @@ TEST_F(NormInputRecomputationTest, RecomputeRelu) {
  ASSERT_EQ(relu_grad2->operand(0), relu1);
  - CompilerAnnotations annotations(module);
  - ModuleFlatten flatten(annotations);
  - ConvolutionClassifier classifier(annotations);
  - CustomOpReplacer replacer{};
  -
  - auto replacer_res = replacer.Run(module);
  -
  - EXPECT_TRUE(replacer_res.ok());
  - EXPECT_TRUE(replacer_res.ValueOrDie());
  -
  EXPECT_TRUE(flatten.Run(module).ValueOrDie());
  auto res = classifier.Run(module);
  