[clang] [clang][NFC] Annotate `Type` bit-fields with `clang::preferred_type` (PR #70349)

[Vlad Serebrennikov via cfe-commits]

Endilll wrote:

@tbaederr As highlighted in https://github.com/llvm/llvm-project/pull/69104, this attribute doesn't change semantics of the program, so it's safe to ignore.

https://github.com/llvm/llvm-project/pull/70349