resolve_cassandra_config did not accept replication_factor as a kwarg,
so cassandra_replication_factor from YAML params was silently ignored
by all 6 callers. Add the kwarg and pass it from every caller.
Same fix for Qdrant: 3 writers now pass qdrant_replication_factor and
qdrant_shard_number from params.
Add tests covering the params path for both helpers.
