IT test for fine-grained recovery (task executor failures)

The BatchFineGrainedRecoveryITCase can be extended with an additional test failure strategy which abruptly shuts down the task executor. This leads to the loss of all previously completed and the in-progress mapper result partitions. The fail-over strategy should restart the current in-progress mapper which will get the PartitionNotFoundException because the previous result becomes unavailable and the previous mapper has to be restarted as well. The same should happen subsequently with all previous mappers. When the source is recomputed, all mappers has to be restarted again to recalculate their lost results.