Synchronize submodules with LLVM at llvm/llvm-project@55c71c9eac9b

Updates LLVM dependencies to match
[55c71c9eac9b](https://github.com/llvm/llvm-project/commit/55c71c9eac9b).
- TensorFlow to
[f435ae9dee67](https://github.com/tensorflow/tensorflow/commit/f435ae9dee67)
- MLIR-HLO to
[4d4adc2e0dd7](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: 417682731