[clang] [clang] apply clang-tidy's llvm-redundant-casting (NFC) (PR #191322)

[Henrik G. Olsson via cfe-commits]

hnrklssn wrote:

This is a follow up to https://github.com/llvm/llvm-project/pull/189106, which only addressed `dyn_cast`. This one addresses both `cast` and `dyn_cast`, and their variants `_or_null`/`_if_present` variants.

https://github.com/llvm/llvm-project/pull/191322