eventscript: fix monitoring when killed by another script command

eventscript: fix monitoring when killed by another script command

Commit c1ba1392fe "eventscript: get rid of ctdb_control_event_script_finished
altogether" was wrong: there is one case where we want to free the script
without transferring their status to last_status.  This happens because we
always kill an running monitor command when we run any other command.

This still isn't quite right (and never was): the callback will be called
with status value 0, which might flip us to HEALTHY if we were unhealthy.
This is conveniently fixed in my next set of patches :)

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>