De-duplicate *_preserve and *_preseve_min

I had quite a hard time understanding the difference between the `*_preserve` and `*_preseve_min` config options after misunderstanding them in the beginning.

After reading them in more detail now, I don't understand why this differentiation even exists. AFAICS, by just always having one of them and allowing the values ` all|latest|no|`, all use cases covered at the moment would then be achievable as well.
As a result, configuration would be much easier and less error-prone.