fix order of finalization (algs before scheduler)

@ahennequ @clemenci fyi

the scheduler needs to be finalized after the hivedatabroker, because this is the one taking care of algorithm finalization.
Therefore, we assign a higher priority to the broker than to the scheduler (which is 10*default_priority)
Not the nicest solution, but since finalization order is revisited soon anyway, another hack can not hurt 😏