`TestCatFileBatch/QueryTerminated` relied on timing to distinguish
`os.ErrClosed` vs `io.EOF` error paths. Replace `time.Sleep`-based
synchronization with a channel-based hook on pipe close, making both
error paths fully deterministic regardless of CI runner speed.
Ref: https://github.com/go-gitea/gitea/actions/runs/24193070536/job/70615366804
Co-authored-by: Claude (Opus 4.6) <noreply@anthropic.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>