Get latest Xray sync status for a batch of plans

Returns the most recent Xray sync AsynchronousJob for each requested plan's latest plan run, keyed by plan_id. Plans with no such run, and plans whose latest run has no sync job, are omitted from the result. Unlike a plan-run-keyed lookup this resolves the latest run server-side, so a plan whose last run was up to 400 days ago still reports its sync outcome. Latest-run resolution sees completed runs only and is updated asynchronously, so shortly after a run finishes this may still report the previous run — each status carries the plan_run_id its job belongs to.