BUG: ValueError when printing a DataFrame with DataFrame in its attrs

[yuanx749]

• closes BUG: ValueError when executing a DataFrame with another DatFrame in its attrs #60455(Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• 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.

pandas/pandas/io/formats/format.py

Lines 697 to 699 in a4fc97e

	_len = len(self.tr_frame)
	_slice = np.hstack([np.arange(row_num), np.arange(_len - row_num, _len)])
	self.tr_frame = self.tr_frame.iloc[_slice]

[yuanx749]

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.

[mroeschke]

Looks good. Could you add a whatsnew entry in v3.0.0.rst?

[yuanx749]

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.

[mroeschke]

Thanks @yuanx749

[kaba439]

Many thanks @yuanx749