[Bug] statsItem.samplingInHour trims the wrong list, so csListDay grows without bound and day-level stats use an ever-growing window

[wang-jiahua]

Describe the Bug

statsItem.samplingInHour() in consumer/statistics.go appends a snapshot to csListDay but trims csListHour:

si.csListDay.PushBack(callSnapshot{...})
if si.csListDay.Len() > 25 {
    si.csListHour.Remove(si.csListDay.Front())   // wrong list
}

container/list.Remove(e) is a no-op when e does not belong to that list, so nothing is ever removed: csListDay grows by one snapshot per hour per statsItem forever. The sibling methods samplingInSeconds/samplingInMinutes push and trim the same list, which shows this is a copy-paste slip.

Steps to Reproduce

Call samplingInHour() 30 times on a fresh statsItem; csListDay.Len() is 30 instead of the intended cap 25.

What Did You Expect to See?

csListDay capped at 25 entries (a ~25-hour sliding window for the day-level stats).

What Did You See Instead?

Unbounded growth (slow memory leak, one snapshot per hour per topic/group statsItem), and getStatsDataInDay() computes over an ever-growing window instead of the intended ~25-hour one, skewing day-level TPS/AVGPT.

Additional Context

Fix incoming: si.csListDay.Remove(si.csListDay.Front()), aligning with the sibling sampling methods; includes a regression test.