TST: split up tests/plotting/test_frame.py into subdir & modules #34769
Created instead of #37538

- [x] closes #34769
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

I moved the file to a new directory.
What is the best structure for this folder?

[before_test_ploting_frame](https://gist.github.com/Mikhaylov-yv/999de1451e8ecc836215b30db34ef841)
[after_test_ploting_frame](https://gist.github.com/Mikhaylov-yv/98eca32c21f59cc9e7653cd96d5fabd2)
in pre-commit:

```pandas/tests/plotting/frame/test_frame_groupby.py:7:1: F401 'pandas as pd' imported but unused```

also merge master and ping on green. I am very sorry. I don’t understand what to do next? > I am very sorry. I don’t understand what to do next?

run `git pull upstream master` to merge master, then in the new files use `from pandas import foo` instead of `pd.foo` Thanks @jbrockmendel. After that, I get a message like this:
![image](https://user-images.githubusercontent.com/44315225/98464889-e8f4b000-21d6-11eb-9f1b-0722a8f7219e.png)
Am I doing the right thing?
 Hello @Mikhaylov-yv! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:









There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2020-11-12 05:34:48 UTC > Am I doing the right thing?

I dont see anything wrong in the screenshot you posted.

Near the bottom of this page you should see a box with red text saying "Some checks were not successful".  In that box there are two red "x"s for the failed checks.  Click through to the details on those to see what still needs to be addressed. @jbrockmendel Thanks. I think I figured out what to do. I hope I took into account all my mistakes The errors don't seem to be relevant to my pull request. I'm wrong? > The errors don't seem to be relevant to my pull request. I'm wrong?

You are not wrong.  This is affecting all the builds, you can ignore this failure for now. Thanks @jbrockmendel Does this mean the job is ready?  or do you need to do something else? @Mikhaylov-yv is this pretty much cut/paste?  if so, can you merge master and ping on green @jbrockmendel Yes it is.  the number of tests is the same as the master.  
Now I'm going to merge LGTM cc @jreback thanks @Mikhaylov-yv  @jreback @jbrockmendel  Thank you very much for your help