TMSS-1144: set provenance chain subtasks to finished. Do not alter dataproducts (which is now forbidden), but test on new instances

TMSS-1144: skip non-finished and/or obsolete subtasks, as they are not part of the successfull provenance chain

TMSS-1124: added missing TaskTemplateExtendedSerializer for specifications_template of TaskDraftExtendedSerializer

TMSS-1124: using first is ok according to !633 (comment 24581)

TMSS-1124: create a subtask_output per task_connector_type of the task, but only with role Correlator or Beamformer because that is what observations produce

TMSS-1124: fetch the subtask's input/output dataproducts and all related properties in one queryset. Major speedup

TMSS-1124: use newly implemented SubtaskInput/Output to filter and connect the correct dataproducts between subtasks