[clang] [clang][Interp] Implement IntegralAP subtraction (PR #71648)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

Feel free to ignore the suggestions if you think they're not useful, but I tend to prefer not using a local variable for something used as a functor unless it's going to be reused.

Generally LG but I'd prefer to hold off on approval until CI is green with the changes.

https://github.com/llvm/llvm-project/pull/71648