[clang] [Clang] Use getNonTypeTemplateArgumentType fallback in getTypeOfConstantTemplateParameter (PR #231983)

[Corentin Jabot via cfe-commits]

https://github.com/cor3ntin approved this pull request.

I'd very much like to have tests for that but i can't really come up with one, and i don't want us to leave the codebase as-is so, unless someone has an idea how to test that change in the next day or 2, LGTM

https://github.com/llvm/llvm-project/pull/231983