Probabilities map reordering issue

With the dask scheduler, classifications tasks can be launched before all models was trained.

In this case, if the number of class is different for all regions this may cause an issue for know all classes available.

For instance, 3 models must be learned: the first with 12 classes, second with only 3 and last with 19 (and 19 is the total number of classes for this run)

If the third model is learn first, then no issue.

If the two first models are learned and the classification start, the ordered probability maps will have 12 bands. Then when the first model is learned and the classsification done, the last probability map will have 19 bands.