[clang] Suppress errors from well-formed-testing type traits in SFINAE contexts (PR #135390)

[Aaron Puchert via cfe-commits]

aaronpuchert wrote:

Could also add this under "Bug Fixes to C++ Support". The entries about type traits [don't seem to be consistently categorized](https://releases.llvm.org/19.1.0/tools/clang/docs/ReleaseNotes.html#bug-fixes-in-this-version), but I think this is all C++-only.

https://github.com/llvm/llvm-project/pull/135390