Remove "Fake cave" generation for 1.17

Everyone who has played survival more than once, has probably found a promising cave opening that has lead only to dissapointment as your adventure underground ends with a Rocky dead-end, sooner than expected. The mayority of people, if not the entire playerbase, can agree that this (probably accidental) feature can get really stressful/annoying and that it doesn't have a good reason to exist ever since caves cover every purpose this feature can grant. So for the 1.17 update i propose the removal of these Fake caves as they seem useless in their current state. As an alternative, adding a visual differentiator visible from the entrance for these two types of caves could also do the job.