fix(compactor): fix unschedule groups

[Li0k]

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What's changed and what's your intention?

The unscheduled logic is not triggered when the batch compaction fails to get any task. This results in the flag not being cleared, and the same type of compaction being triggered all the time, leading to starvation.

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[Little-Wallace]

LGTM

[hzxa21]

LGTM