[llvm] [RemoveDIs] Update DIBuilder C API with DbgRecord functions. (PR #95535)

[Orlando Cazalet-Hyams via llvm-commits]

OCHyams wrote:

> I do have to wonder whether LLVM[Set]IsNewDbgInfoFormat is useful? Given that the APIs for inserting old info no longer exist.

We needed it in tests while transitioning. There's a chance it might be useful still for downsteam projects still atm (allows a producer flip back to the old format after inserting the records). It won't be useful in the future once intrinsics have been completely removed (hence the planned deprecation).

I'm not sure it's doing much harm and could potentially be helpful, but I don't have strong feelings about it. If you think that the clutter isn't warranted we could remove that too (maybe in a separate commit to keep things moving?). 

https://github.com/llvm/llvm-project/pull/95535