Revert "[clang] template / auto deduction deduces common sugar"

Revert "[clang] template / auto deduction deduces common sugar"

This reverts commit d200db38637884fd0b421802c6094b2a03ceb29e, which causes a
clang crash. See https://reviews.llvm.org/D111283#3785755

Test case for convenience:
```
template <typename T>
using P = int T::*;

template <typename T, typename... A>
void j(P<T>, T, A...);

template <typename T>
void j(P<T>, T);

struct S {
  int b;
};
void g(P<S> k, S s) { j(k, s); }
```