sct_deepseg_sc: use CLAHE by default for QC
sct_deepseg_sc: use CLAHE by default for QC


Former-commit-id: 3f599fbc6e3f893b822ab73872175e46533d8928
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox