Failed to split a symbolic allocation domain.

[wujingyue]

This is a spin-off from #3458 (comment).

Repro:

Fuser/tests/cpp/test_allocation_domain.cpp

Lines 1441 to 1464 in 7e2e6fa

	// The test fails as is. The symbolic IterDomains in loop/allocation are not
	// concretized. I tried to change DynamicTransformConcretizer::mutate to grab
	// all expressions between root and allocation but still couldn't get it to
	// work.
	TEST_F(AllocationDomainTest, DISABLED_InputAllocationIsSplit_Symbolic) {
	auto fusion = std::make_unique<Fusion>();
	FusionGuard fg(fusion.get());
	TensorView* in = makeContigTensor(1);
	TensorView* out = set(in);
	fusion->addInput(in);
	fusion->addOutput(out);
	in->split(0, 2);
	in->setAllocationDomain(in->getLoopDomain(), true);
	FusionExecutorCache executor_cache(std::move(fusion));
	auto options = at::TensorOptions().dtype(at::kFloat).device(at::kCUDA);
	at::Tensor in_tensor = at::randn({6}, options);
	auto out_tensors = executor_cache.runFusionWithInputs({in_tensor});
	testValidate(
	executor_cache.fusion(), out_tensors, {in_tensor}, __LINE__, __FILE__);
	}

$ bin/nvfuser_tests --gtest_filter=*InputAllocationIsSplit_Symbolic --gtest_also_run_disabled_tests

C++ exception with description " INTERNAL ASSERT FAILED at "/opt/pytorch/nvfuser/csrc/ir/utils.cpp":965, please report a bug with repro script to NVFuser at https://github.com/NVIDIA/Fuser/issues. dom0 has unreachable IDs. dom0: iS27{( (( (( getMetaData(T0) )).logical_size ))[0] )}. dom1: iS2{( ceilDiv(i0, 2) )}, iS3{2}

Apparently, replaceSymbolicSizes failed to replace the symbolic sizes in the allocation/loop domain, leading to a disconnected ID graph.