Fix the integrity checker so that it can correct workflow steps in the 'KILLED' state

The WorkflowStateCheck integrity checker currently only corrects workflow entries where the state is null or 0. We recently had a case on EACJ where the state was incorrectly set to 3 (KILLED) for a number of issues. We should improve this check so that it can fixed up issues in this state as well as well as state 4 "Unknown".

Just need to verify though when issues really are meant to be in the KILLED state. There may be some legitimate reasons for an issues workflow entry to be in this state.