[llvm] [llvm] Use StringRef::{starts,ends}_with (NFC) (PR #74956)

[Felipe de Azevedo Piovezan via llvm-commits]

felipepiovezan wrote:

> LGTM - I couldn't see any clang-format warnings that were particularly severe (just code alignment etc.) - its up to you if you format them or not.

Most of those are about 80 characters/line. 
IMO we should not be introducing code that is not clang-format clean, just like with any other PR

https://github.com/llvm/llvm-project/pull/74956