Align disk cleaning with disk_species_clean.sh

[alexbelgium]

#256

[alexbelgium]

Allow to have a single logic for deleting old files.

Old logic : "delete all files older than 90 days not in the exclude_files until reaching the right free space ; if not enough, purge PROCESSED folder (that was already removed from this fork)"
New logic : "delete files in order to free 10% of additional space with the following priorities : protect files that have less than 7 days, protect files in the exclude_files, and start deleting files with the lowest confidences with first the species with highest files".

This should allow to standardize disk clearance in a way that saveguards important files : species with less recordings, and recordings with higher confidence