Currently when using `unit` parameter in the `rate` aggregator in time series mode (meaning the `rate` aggregation is defined as a child aggregation of `time_series` aggregation) then this parameter is ignored. We should investigate whether this parameter can be supported for computing rate in time series mode.
x-pack/plugin/analytics/src/main/java/org/elasticsearch/xpack/analytics/rate/TimeSeriesRateAggregator.java
currentStartTime = aggCtx.getTimestamp();
                    currentStartValue = checkForResets(latestValue);
                }
            }
        };
    }
    @Override
    public InternalResetTrackingRate buildAggregation(long owningBucketOrd) {
        calculateLastBucket();
        return new InternalResetTrackingRate(
            name,
            DocValueFormat.RAW,
            metadata(),
            startValues.get(owningBucketOrd),
            endValues.get(owningBucketOrd),
            startTimes.get(owningBucketOrd),
            endTimes.get(owningBucketOrd),
            resetCompensations.get(owningBucketOrd)
        );
    }
    @Override
    protected void doClose() {
        Releasables.close(startValues, endValues, startTimes, endTimes, resetCompensations);
    }
    @Override
    public double metric(long owningBucketOrd) {
        return buildAggregation(owningBucketOrd).getValue();
    }
}