[Developer][Archery] Change items_per_seconds units

[asfimport]

Antoine requested that I change the units in items_per_seconds_fmt to be:

• K items/sec

• M items/sec

• G items/sec

  Rather than:

• k items/sec

• m items/sec

• b items/sec

Reporter: Diana Clarke / @dianaclarke
Assignee: Diana Clarke / @dianaclarke

PRs and other links:

• GitHub Pull Request #9433

_{Note: This issue was originally created as ARROW-11539. Please see the migration documentation for further details.}

[asfimport]

David Li / @lidavidm:
Issue resolved by pull request 9433
#9433