node-agent: data-path 监视器 goroutine 存活超过了自身的 DataUpload CR 被删除, 永久占用了一个 loadConcurrency 位置

While diagnosing a separate DataUpload livelock (matching #9453's symptom shape — DataUploads stuck in `Prepared` with zero progress for 95+ minutes, zero bytes moved, no errors at INFO level), we took a live goroutine dump of a `node-agent` pod before restarting it (`kubectl debug --target <pod> --image=busybox --target=node-agent -- sh -c 'kill -QUIT <pid>'`, since the distroless `velero` image ships no shell to send the signal directly).