Blue band read

https://gitlab.orfeo-toolbox.org/remote_modules/let-it-snow/-/blob/int_stage_roman/python/s2snow/fsc_config.py#L313

these lines are wrong, it resets the blue band path to None if it was previously loaded using find_files..

else:
    self.blue_band_no_band = 1
    self.blue_band_path = None