Tutorial: Update all screenshots to match the new 80/10/10 split (+ Arkindex modal buttons)

Refs https://redmine.teklia.com/issues/8102, from https://redmine.teklia.com/issues/7670

Followup from #117 (closed)

We need to update all screenshots still showing 471 selected pages previously added in our dataset. We now only have 100 pages in it. This impacts lots and lots of screenshots accross the tutorial (ground truths, trainings, etc).

In the meantime, we can also retake screenshots where Arkindex modal buttons have moved, some work was done in frontend!1688 (merged) to unify the display and our screenshots were taken before this harmonization.