OPT: added ITK number of thread limit for testing pipeline
OPT: added ITK number of thread limit for testing pipeline

Former-commit-id: a65132587ac816ea2ab708331f65f637e58264b8 [formerly cf4726e31e39bba02e8bd3c2e1643cf073caba36]
Former-commit-id: 3eedb50ff97219a6f8fd636721e3bd9e4c49d38a
Former-commit-id: ba9a20e2c2758a6dcd5ff1014bc2797b56341262
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox