Synchronize submodules with LLVM at llvm/llvm-project@9b6c8132d378

Updates LLVM dependencies to match
[9b6c8132d378](https://github.com/llvm/llvm-project/commit/9b6c8132d378).
- TensorFlow to
[0a5d008b77c1](https://github.com/tensorflow/tensorflow/commit/0a5d008b77c1)
- MLIR-HLO to
[4ae8dea1857c](https://github.com/tensorflow/mlir-hlo/commit/${MLIR_HLO_SHA?})

`./scripts/git/update_to_llvm_syncpoint.py`

Automated submodule bump from .github/workflows/update_llvm_dependent_submodules.yml

PiperOrigin-RevId: 394331861