[clang] [Clang][Sema] Disable checking invalid template id in initializer of primary variable template `std::format_kind` with libstdc++ (PR #139560)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

Can you add a test for this too?  

https://github.com/llvm/llvm-project/pull/139560