[clang] [Clang][Concepts] Fix the constraint equivalence checking for TemplateTypeParmTypes (PR #102131)

[Younan Zhang via cfe-commits]

zyn0217 wrote:

@mizvekov suggested in https://github.com/llvm/llvm-project/issues/101735#issuecomment-2273950029 we should try to decouple the constraint checking from the redeclaration chain building, however that is somehow involved.

https://github.com/llvm/llvm-project/pull/102131