BUG: IndexError on read_csv/read_table when using usecols/names parameters and omitting last column

This addresses an issue in read_csv/read_table where there is no header and both usecols and names are assigned but the last column is not included. This caused an IndexError after reaching the last column specified in usecols. Existing test cases for `usecols` were modified to expose and address this specific issue.

#5766