[clang] Fix implementation of [temp.param]p14's first sentence. (PR #83487)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

The changes look correct to me, but I think we should add a DR test for this so that we can properly regenerate cxx_dr_status.html

Also, the changes should come with a release note.

https://github.com/llvm/llvm-project/pull/83487