[content assist] Anonymous inner class has wrong type parameters

Original issue: https://bugs.eclipse.org/bugs/show_bug.cgi?id=572825

If I have
```
public class MyMap implements Map {

@Override
public Set keySet() {
return new Set<== Content assist trigger
}
}
```
and want to create an anonymous set in keySet() then content assist creates
```
return new Set() {
};
```
The `MyMap.K` is incorrect. Content assist should generate
```
return new Set() {
};
```
Note that the quick fix suggests changing `MyMap.K` to `K`.

This bug still shows up with Eclipse 4.33 (2024-09).