alternator: add bumping filtering stats
alternator: add bumping filtering stats

When filtering is used in querying or scanning, the number of total
filtered rows is added to stats.

avikivity/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla