Improve BloomFilter's size estimation

[simerplaha]

Description

Initial byte size estimation bloom-filters in some cases is high. I'm seeing the estimation being 8 times more than actual when the key is a simple Integer.

Estimated size: 143776 bytes Actual size: 17976 bytes

Issue

Compaction would allocate larger byte arrays than required to build bloom-filters.

Solution

Improve BloomFilter estimation of optimal size.