Truncate columns list to match tr_frame for correct dict formatters lookup
When using a dictionary of formatters and a truncated DataFrame is being displayed, the column list used for looking up the formatter in the dict are incorrect.  The columns attribute of the DataFrameFormatter needs to be truncated as well for the lookup to be correct.

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