compileTimeOnly does not work on a trait/class

## Minimized code

```Scala
@annotation.compileTimeOnly("Foo should be erased") trait Foo
@annotation.compileTimeOnly("Bar should be erased") class Bar
val foo = new Foo {}
val bar = new Bar {}
```

## Output

compiles ok

## Expectation

error `Foo should be erased`, `Bar should be erased`, as in Scala 2.13