CLN: Removed class in pandas/tests/series/test_timezones.py
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`


This is similar to #32184. Nothing in the tests changed, I just removed the unused class interface to simplify the file As we're not using any functionality of the class interface, then why have it? Having the class means...
1. it's harder to reason about the test: functions are more independent than methods
1. it forces `black` to use more line breaks (we reach the line limit earlier because of the extra indentation)
1. it adds more clutter

I think the class interface is just a left-over from #22550 > As we're not using any functionality of the class interface, then why have it? Having the class means...
> 
> 1. it's harder to reason about the test: functions are more independent than methods
> 2. it forces `black` to use more line breaks (we reach the line limit earlier because of the extra indentation)
> 3. it adds more clutter
> 
> I think the class interface is just a left-over from #22550

@SaturnFromTitan I get it, and generally i agree, however i also think we have *many* of these, so we are talking many PRs; so unless we are splitting out to separate modules I wouldn't change this. 

Now I could be wrong on the number, if you want to see how many single file with a class we have then I could change. Gotcha. Indeed, there are 100+ files like that.

Even though the effort to change this is very small, I guess the review effort would be significant and would be better to be invested elsewhere. Closing this then