[clang] Bugfix for chosing the correct deduction guide (PR #66487)

[Shafik Yaghmour via cfe-commits]

shafik wrote:

I added a comment in the issue her: https://github.com/llvm/llvm-project/issues/67959#issuecomment-1743564143

Please make sure to add references to the standard in appropriate places in this PR.

https://github.com/llvm/llvm-project/pull/66487