findApertures fooled by negative images from ABBA in longslit stacked data

[KathleenLabrie]

findApertures fails to correctly identify the sources in an aligned and stacked ABBA 2-D spectrum. The negative images appear to be fooling the algorithm.

See screenshot for the interactive window of findApertures.

To reproduce:

reduce N20170609S0127_stack.fits -r findApertures -p interactive=True

The stack can be found here: https://drive.google.com/drive/folders/14sssXLi93VYdqOF3Mhm9AK1h8_1tnyR0?usp=sharing

[On Oct31, 2023, was using branch feature/niri_wavecal_merge_with_master]