perf: use `setup` function in `perfdirfoldmap`
The command seems to pre-date the introduction of the `setup` support in timer.
We move the line that is obviously about benchmark setup in such `setup`
function.
[tool.black]
line-length = 80
exclude = 'build/|wheelhouse/|dist/|packages/|\.hg/|\.mypy_cache/|\.venv/|mercurial/thirdparty/|hgext/fsmonitor/pywatchman/|contrib/python-zstandard/'