[llvm] [llvm] Drop "const" from "const ArrayRef" (NFC) (PR #138818)

[Jay Foad via llvm-commits]

https://github.com/jayfoad commented:

LGTM but this is not specific to ArrayRef, it is just a special case of const return type: https://clang.llvm.org/extra/clang-tidy/checks/readability/const-return-type.html

https://github.com/llvm/llvm-project/pull/138818