Cave generation 21w08a

Based on my feedback from last week. that says

"In the current snapshot 21w07a. they reduced the amount of big caves that spawn.(understandable in a way since it was a lot of cave. but it seems that the big caves are a bit to rare as of 21w07a. been flying around and barely could find anything and when found it wasn't that impressive as last week snapshot. hope it can get tweaked soon to be a bit more. otherwise excellent work on the snapshots!"

This week we've saw mayor tweaks of the cave generation and the big caves are way more common thank you for this!

The only tweak I think it could use is normal cave generation between the giant caves. still feels a tiny bit barren between the big ones (correct me if this was already confirmed). and maybe a few more giant caves please.

Again thank you for an amazing snapshot this week!