[clang] [LifetimeSafety] Avoid suggesting lifetimebound attribute on primary templates declarations (PR #203866)

[Gábor Horváth via cfe-commits]

Xazax-hun wrote:

Do we still warn on the primary template here:

```
template <typename T>
T &foo(T &obj) { return obj; }

// later: f(x); where x is int.
```?



https://github.com/llvm/llvm-project/pull/203866