public Load peakLoad() {
        return new Load(peakLoad(Load.Dimension.cpu), peakLoad(Load.Dimension.memory), peakLoad(Load.Dimension.disk),
                        peakLoad(Load.Dimension.gpu), peakLoad(Load.Dimension.gpuMemory));
    }
Returns the "peak load" in this: Which is for each load dimension,
the average of the highest reading for that dimension on each node.
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/ClusterNodesTimeseries.java