[lldb][NFC] Replace const std::vector& with ArrayRef in APIs (#170834)
Inside the LLVM codebase, const vector& should just be ArrayRef, as this
more general API works both with vectors, SmallVectors and
SmallVectorImpl, as well as with single elements.
This commit replaces two uses introduced in
https://github.com/llvm/llvm-project/pull/168797 .