This series adds a histogram for get and write batch sizes.
It uses the estimated_histogram implementation which starts from 1 with 1.2 exponential factor, which works
extremely tight to 20 but still covers all the way to 100.
Histograms will be reported per node.
**Backport to 2025.1 so we'll have information about user batch size limitation**
Closesscylladb/scylladb#23379
* github.com:scylladb/scylladb:
alternator: Add tests for the batch items histograms
alternator: Add histogram for batch item count