[clang] [clang] fix broken canonicalization of DeducedTemplateSpecializationType (PR #95202)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

I feel better to have a regression test for this if possible. I am just worrying someone someday meet the problem unconsciously.

https://github.com/llvm/llvm-project/pull/95202