Use of `"target_suffix": ["_lesion-manual"]` leads to multiple targets during training and testing

[uzaymacar]

As discussed in more detail in https://github.com/ivadomed/ivadomed/issues/1055, I recently discovered that the use _lesion-manual as the target suffix leads to ivadomed using all derivatives which have the _lesion-manual string in it (e.g. _lesion-manual.nii.gz, _lesion-manual-majvote, _lesion-manual2.nii.gz, etc.).

This creates inconsistencies in training and testing. For example, running ivadomed --test -c config/test_on_rater1.json yields different results in each run as a different GT is selected from the derivatives that contain the _lesion-manual string.

As mentioned in the ivadomed issue linked above, a quick fix for now is to update the "target_suffix" to include the .nii.gz file extension. This is because the target suffix string _lesion-manual.nii.gz breaks the overlap between the filenames _lesion-manual.nii.gz and _lesion-manual2.nii.gz (and also the other derivatives).

The next steps are to:

• [x] Update all config files to include the .nii.gz extension in the "target_suffix" key (will link a PR soon)
• [x] Re-train and re-test lesion segmentation (note: no need to do this for SC segmentation as we have one label for this task)

[jcohenadad]

Not needed anymore as we are now using a single-rater segmentation (_NeuroPoly)