Sparse load of sparse primary key index

**Use case**
Reduce memory usage in case of big tables/big parts with a lot of rows and default index granularity

**Describe the solution you'd like**

Primary key can be loaded with some sparse factor, which will does mean that CH will load every X mark instead of every mark.
Sparse factor can depend on number of rows in part, so big parts from table will bigger factor value.

**Describe alternatives you've considered**

https://github.com/ClickHouse/ClickHouse/issues/71992, but i do think, that it may work better than cache for index.