[clang] [clang-tools-extra] Remove `StringLiteral` in favor of `StringRef` (PR #122366)

[Benoit Jacob via cfe-commits]

bjacob wrote:

@s-barannikov 

> > * the `strlen` is NOT constant-evaluated on MSVC, even the latest version.
> 
> The godbolt link shows otherwise?

This is what I see in godbolt - to me this loop looks like strlen:

![{FBB342A5-7B03-4AD6-AB88-01686E1D9B69}](https://github.com/user-attachments/assets/8798ffee-b792-436f-b944-377a25fd8b2e)


https://github.com/llvm/llvm-project/pull/122366