Try:
| eval OverAllStatus=case(jobStatusSummary="Success", "Pass", jobStatusSummary="NoBackUp", "NoBackUp", jobStatusSummary!="Success", "Fail") | streamstats last(OverAllStatus) AS OverAllStatus BY machine
That assumes the first event per host already have an OverAllStatus value. If it is possible that value won't be present for the first event per machine you may try this:
| eval OverAllStatus=case(jobStatusSummary="Success", "Pass", jobStatusSummary="NoBackUp", "NoBackUp", jobStatusSummary!="Success", "Fail") | eventstats last(OverAllStatus) AS OverAllStatus BY machine
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