[clang] [Clang][Sema] Use correct TemplateName when transforming TemplateSpecializationType (PR #93411)

[Matheus Izvekov via cfe-commits]

https://github.com/mizvekov commented:

The problem here is the loss of the qualification on the TemplateNames

This patch fixes the problem, without taking any workarounds: https://github.com/llvm/llvm-project/pull/93433

It also doesn't cause any change in diagnostics in `clang/test/SemaTemplate/typename-specifier-3.cpp`.

https://github.com/llvm/llvm-project/pull/93411