BUG: ValueError when printing a DataFrame with DataFrame in its attrs
- [x] closes #60455(Replace xxxx with the GitHub issue number)
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [x] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

This PR replaces `concat` with slice in `_truncate_horizontally` as in `_truncate_vertically` to avoid the ValueError.
https://github.com/pandas-dev/pandas/blob/a4fc97e92ed938260728e3f6c2b92df5ffb57b7f/pandas/io/formats/format.py#L697-L699

Hmm, I don't understand why there is a mypy error after this change:
 pandas/io/formats/string.py:82: error: Cannot determine type of "tr_col_num"  [has-type]

I don't get this error locally. > Looks good. Could you add a whatsnew entry in `v3.0.0.rst`?

Not sure where the right place is, I added in the `Other` section. Thanks @yuanx749  Many thanks @yuanx749 