SubviewAttributeFlusher always cascade deletes

[beikov]

When removing OwningView that contains Subview, regardless of the cascading mapping, it will always remove the entity for Subview as well. This must be fixed.

@EntityView(OwningEntity.class)
interface OwningView {
  //...
  Subview getSubview();
}
@EntityView(SubEntity.class)
interface Subview {
  //...
}