Directory not removed on failed run

[csatt]

This is a longstanding problem, presumably since the run_info file was added.

When there is a failure like Isc polling timeout, the whole directory is supposed to be removed by the clean_up_after_failure() method in IV_Swinger2.py. But that method inferred that if the run directory had two files, they were the ADC CSV file and the data points CSV file and it would not remove the directory. But when there is a run_info file (for sensor info), the directory is not removed because it contains the ADC CSV file and the run_info file.

This was a terrible way to determine that the directory contained these two files. It should be explicit.