DPC++ daily 2021-12-12

[CI] Use clang-format from nightly builds (#5126)

[Contributing guide](https://github.com/intel/llvm/blob/sycl/CONTRIBUTING.md) suggests using the same version of clang-format, that is build from tip of this repository. That caused problems in the past, where the newer clang-format does the job differently to what's being used in CI. This patch switches to default clang-format installation to the one, that comes with nightly builds. This would allow us to minimize the impact of different clang-format versions.