Get SPE file location always from importlib resources absolute path

[morcuended]

cta-lstchain/lstchain/image/modifier.py

Lines 526 to 531 in cfd9a7f

	spe_location = (config['waveform_nsb_tuning']['spe_location']
	if 'spe_location' in config['waveform_nsb_tuning']
	and config['waveform_nsb_tuning']['spe_location']
	is not None
	else get_resource_path(
	"data/SinglePhE_ResponseInPhE_expo2Gaus.dat"))

For the spe file, I would always use the get resource path here getting the path from importlib resources instead of trying first to search for the path in the config file.

It happens to me that the path in the lstchain config used for DL1 production was defined as "lstchain/data/SinglePhE_ResponseInPhE_expo2Gaus.dat" which does not define the absolute path, hence failing.