[clang] [clang][AST] Fix end location of DeclarationNameInfo on instantiated methods (PR #92654)

[via cfe-commits]

Abramo-Bagnara wrote:

@alejandro-alvarez-sonarsource @steakhal 

This breaks the type info loaded correctly in previous decl instantiation:

```
template <typename T>
struct s {
  operator T();
    return 0;
  }
};

void f() {
  s<int> x;
  (int)x;
}
```

In this case the instantiated conversion DeclarationNameInfo is reverted back to template parameter T, instead of correct SubstTemplateTypeParmType.

https://github.com/llvm/llvm-project/pull/92654