Deprecate prefix argument in read_csv and read_table
- [x] closes #43396
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit) for how to run them
- [x] whatsnew entry

cc @lithomas1 I am also on board with deprecating this. I don't think the keyword adds real value

Using ``parser.read_csv_check_warnings`` should fix the stacklevel issues. 
https://github.com/pandas-dev/pandas/blob/bdff2148ec5c81b2724ac77b3138d229994cffc4/pandas/tests/io/parser/conftest.py#L31-L39

It would be also nice to add an example to the user guide of how to add a prefix to the names. thanks @phofl 