[clang] [Clang] Fix ICE in constraint normalization when substituting concept template parameters (PR #184406)

[Corentin Jabot via cfe-commits]

https://github.com/cor3ntin commented:

Thanks for fixing that. And thank to @zyn0217 for the great review.
The change makes sense to me, i just have a small nit.

I think we need a release note for that fix. I don't think it warrants a backport given that it's a recent C++26 feature

https://github.com/llvm/llvm-project/pull/184406