[Developer][Archery] Move benchmark tests (so CI runs them)

[asfimport]

I recently added additional tests to:

https://github.com/apache/arrow/blob/master/dev/archery/tests/test_benchmarks.py

But just noticed that they aren't actually being executed by CI (because they aren't in the expected location):

      - name: Archery Unittests
        working-directory: dev/archery
        run: pytest -v archery

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

PRs and other links:

• GitHub Pull Request #9564

_{Note: This issue was originally created as ARROW-11771. Please see the migration documentation for further details.}

[asfimport]

Kouhei Sutou / @kou:
Issue resolved by pull request 9564
#9564