INST: install_sct: add path at the beginning to overwrite previous SCT declarations
INST: install_sct: add path at the beginning to overwrite previous SCT declarations

Former-commit-id: 6e4b8f3093952e7a38fde65188ed8755ca33a99f
Former-commit-id: 9a6195849af52c2f64a231aeeb0a7527b6fab445
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox