fix(summarize_dataframe): remove duplicated missing index

[fangliu117]

The original code still prints the list of row indices even when print_nan_locations is  False. It also prints the indices twice when it is True (message + summary), which clutters the log if tens of thousands of rows are missing, dumping all indices to the console can overwhelm CI log.

I have refactored the function code by commenting out the duplicated line that prints the index list inside the summary block, so keeps logs concise, preserves full detail when requested.
It affects only the console output—it does not change what the function returns. Therefore this unit test assertion remains valid.