Fix 5ttgen -template test for 3.0.3
Fix 5ttgen -template test for 3.0.3

Echoes change in 6c9a4dee / ff5e5899, as corresponding change to test data was made in 65a711ec.

MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3