tests: perf: perf_fast_forward: Fix test_large_partition_slicing_clustering_keys for scylla_bench_large_part_ds1 schema
tests: perf: perf_fast_forward: Fix test_large_partition_slicing_clustering_keys for scylla_bench_large_part_ds1 schema

The test case assumed int32 partition key, but
scylla_bench_large_part_ds1 has int64 partition key. This resulted in
no results to be returned by the reader.

Fixs by introducing a partition key factory on the data source level.

Message-Id: <662207576a54eddeacc48f3e7cecc4c8fa05143c@scylladb.com>

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