TMSS-519: Update scheduling_unit_blueprint/<id>/copy_draft; fix issue in create_scheduling_unit_draft_from_scheduling_unit_blueprint

(cherry picked from commit b7734136)

TMSS-703: Refer to blueprint constraints also in tests that were added before that change got merged to master

TMSS-717: enforcing a minimum of one station in the list is too strict, sometimes an empty stationlist is ok.

TMSS-703: Remove cancellation from blueprint creation again (will be handled by scheduler), add is_triggered to draft as well, add tests for blueprint creation

TMSS-703: Cancel running obs on triggered obs, add project property to subtask, modify path_to_project to deal with ManyToMany fields

TMSS-697: remove constraints from blueprint test data again since they get overwritten by draft values anyway

TMSS-697: limit check for constraints change to when original doc was not None, hopefully fixing existing tests