Metrics: some metrics will be loss if operation finished abnormal.

[bufferflies]

Enhancement Task

If the scheduled operator finish abnormal like timeout or cancel, the finish counter will loss.
relate code:

pd/server/schedule/operator_controller.go

Lines 565 to 575 in 056ca9d

	case operator.SUCCESS:
	log.Info("operator finish",
	zap.Uint64("region-id", op.RegionID()),
	zap.Duration("takes", op.RunningTime()),
	zap.Reflect("operator", op),
	zap.String("additional-info", op.GetAdditionalInfo()))
	operatorCounter.WithLabelValues(op.Desc(), "finish").Inc()
	operatorDuration.WithLabelValues(op.Desc()).Observe(op.RunningTime().Seconds())
	for _, counter := range op.FinishedCounters {
	counter.Inc()
	}

[bufferflies]

And I have another question: some counter may be behind if the duration of the operator is high.