Logging of `run_dcm2niix` is not consistent with the conversion result

[NicolasGensollen]

The run_dcm2niix function from the clinica.iotools.bids_utils module logs a "DICOM to BIDS conversion with dcm2niix failed" message whatever the result from the conversion:

clinica/clinica/iotools/bids_utils.py

Lines 895 to 907 in a4984bc

	cprint(
	msg=(
	"DICOM to BIDS conversion with dcm2niix failed:\n"
	f"command: {' '.join(command)}\n"
	f"{output_message}"
	),
	lvl="warning",
	)
	return False
	cprint(
	f"DICOM to BIDS conversion with dcm2niix failed:\ncommand: {' '.join(command)}\n",
	lvl="debug",
	)

The second log should be something like: "DICOM to BIDS conversion with dcm2niix successful".

This inconsistency was introduced in #1029