Currently, KILLED state in SubQuery does not handle any event. As I mentioned in
TAJO-1111, QueryUnit in even terminal states may receive additional unexpected events from a running tasks because a running task reporter sends a progress periodically; that is the report is not synchronized with a task life cycle. As a result, When a killed QueryUnit receives unexpected events, it can cause some event towards SubQuery. But, SubQuery does not handle any addition events if SubQuery is already in KILLED.
This patch adds some transitions to SubQuery in order to fix the above problem.