wa/misc: Fix format_duration() to handle missing time
wa/misc: Fix format_duration() to handle missing time

If a run is interrupted this can cause the time to be `None` causing an
error, if this is the case then set time to 0 and therefore return `N/A`.

setrofim/workload-automation,setrofim/workload-automation,ARM-software/workload-automation,ARM-software/workload-automation,lisatn/workload-automation,ARM-software/workload-automation,lisatn/workload-automation,lisatn/workload-automation,ARM-software/workload-automation,lisatn/workload-automation,setrofim/workload-automation,setrofim/workload-automation