TST: Don't mark all plotting tests as slow
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).

Ideally we should be more targeted regarding a slow test
hmm windows builds taking a long time (but succeeding) > hmm windows builds taking a long time (but succeeding)

Added some `@pytest.mark.slow` to some of the plotting tests (ones in the top 30 slowest) hmm this are you sure we should not mark these slow? seems to be increasing the ci times > hmm this are you sure we should not mark these slow? seems to be increasing the ci times

That would mean _no_ plotting tests would run on MacOS/Windows builds since we're running `not slow`. I was able to discover a PY3.10 entrypoints bug since we weren't running these tests before

IMO testing platform coverage should be more important than CI times since a lot of pandas development is pretty async can we run a slow build on those platforms? > can we run a slow build on those platforms?

I can follow up by removing `not slow` from these builds can you rebase can we reduce the matrix a bit to lower the number of total jobs? Hmm the current jobs were deemed "important" at some point. If we need to prune jobs, my vote would be to remove the 2 locale jobs first.

* Runs a lot of redundant tests
* Relevant tests cannot be targeted
* Encourage users to locally tests, patches accepted, but not practical to test (every locale) in our CI. Similar to our 32 bit testing eventually: https://github.com/pandas-dev/pandas/issues/44453 We could also remove testing pyarrow 6. I think that would reduce 3 builds. for pyarrow oldest and newest are fine (are we testing more)? We're testing 1.0.1 (min), 5, 6, 7 right now. (we're not testing 2 or 3 since we've observed read_csv timeouts with those versions)

IIRC @jorisvandenbossche aimed to test more pyarrow versions since some pandas-pyarrow functionality is only available in certain versions.

 ok then dropping 6 is fine as 5,7 are testing