TST: parametrize in tests/plotting/test_frame.py
- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Parametrize some tests in ``pandas/tests/plotting/test_frame.py``.
/azp run <samp>
Azure Pipelines successfully started running 1 pipeline(s).<br>

</samp> very nice! @ivanovmg if you wouldn't mind can you mark most of these parameterized tests as slow. we are timing out are builds pretty offten: https://travis-ci.org/github/pandas-dev/pandas/jobs/745534073

and its taking like 45min. i don't think in and of themselves these tests are slow, but they do take some time.  the slow builds have more room these tests. > 
> 
> @ivanovmg if you wouldn't mind can you mark most of these parameterized tests as slow. we are timing out are builds pretty offten: https://travis-ci.org/github/pandas-dev/pandas/jobs/745534073
> 
> and its taking like 45min. i don't think in and of themselves these tests are slow, but they do take some time. the slow builds have more room these tests.

Sure, I will go through it and mark the slowish tests as slow. > > @ivanovmg if you wouldn't mind can you mark most of these parameterized tests as slow. we are timing out are builds pretty offten: https://travis-ci.org/github/pandas-dev/pandas/jobs/745534073
> > and its taking like 45min. i don't think in and of themselves these tests are slow, but they do take some time. the slow builds have more room these tests.
> 
> Sure, I will go through it and mark the slowish tests as slow.

great. likley let's mark most / all of them. the fast builds are just taking too long and timing out.