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

[Kazu Hirata via llvm-commits]

kazutakahirata wrote:

> Maybe in the past this was done manually to make code aligned, but manual alignment without the appropriate pragmas will keep perpetuating false-positives from the tools

A good point.  I just ran clang-format on the whole thing.

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