ARROW-11539: [Developer][Archery] Change items_per_seconds units
ARROW-11539: [Developer][Archery] Change items_per_seconds units

Closes #9433 from dianaclarke/ARROW-11539 and squashes the following commits:

4041d49cb <Diana Clarke> ARROW-11539:  Change items_per_seconds units

Authored-by: Diana Clarke <22b83d3550a2682d05bc07a63e9a9fa5dd411e0a@gmail.com>
Signed-off-by: David Li <dc24f9cfc84fb1675ce65c8444a2c3e2f0e5f297@gmail.com>

laurentgo/arrow,laurentgo/arrow,icexelloss/arrow,apache/arrow,laurentgo/arrow,kou/arrow,laurentgo/arrow,kou/arrow,cpcloud/arrow,icexelloss/arrow,icexelloss/arrow,cpcloud/arrow,apache/arrow,icexelloss/arrow,cpcloud/arrow,wesm/arrow,laurentgo/arrow,laurentgo/arrow,wesm/arrow,cpcloud/arrow,kou/arrow,apache/arrow,icexelloss/arrow,laurentgo/arrow,icexelloss/arrow,kou/arrow,apache/arrow,wesm/arrow,wesm/arrow,laurentgo/arrow,icexelloss/arrow,apache/arrow,wesm/arrow,kou/arrow,cpcloud/arrow,apache/arrow,kou/arrow,cpcloud/arrow,icexelloss/arrow,icexelloss/arrow,kou/arrow,cpcloud/arrow,apache/arrow,icexelloss/arrow,laurentgo/arrow,apache/arrow,wesm/arrow,laurentgo/arrow,cpcloud/arrow,cpcloud/arrow,laurentgo/arrow,wesm/arrow,laurentgo/arrow,wesm/arrow,wesm/arrow,apache/arrow,cpcloud/arrow,wesm/arrow,laurentgo/arrow,icexelloss/arrow,wesm/arrow,icexelloss/arrow,apache/arrow,icexelloss/arrow,icexelloss/arrow,wesm/arrow,kou/arrow,kou/arrow,cpcloud/arrow,kou/arrow,kou/arrow,wesm/arrow,laurentgo/arrow,apache/arrow,cpcloud/arrow,apache/arrow,laurentgo/arrow,cpcloud/arrow,apache/arrow,cpcloud/arrow,kou/arrow,apache/arrow,kou/arrow,wesm/arrow,kou/arrow