Fix Bug: last column missing formatting in Latex (#52218)

[corbanvilla]

Still need to write the tests, bug getting this fix started.

• closes BUG: last column name is not bold when applying bold font to column names together with hiding index before converting to latex #52218
• 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.

[attack68]

When you add tests can you test the following:

• A DataFrame with two value columns and an Index. Both values are styled and should have affected output in LaTeX.

The following scenarios:

• The index is a single Index and it is hidden,
• The index is a 3 column MultiIndex and two levels are hidden.
• The index is a 3 column MultiIndex and all levels are hidden.

Thanks.