enhance: switch existing stacked area default chart to be synonymous with owid-distinct
enhance: switch existing stacked area default chart to be synonymous with owid-distinct

Once we do the data migrations we can get rid of the stackedAreaDefault

owid/owid-grapher,owid/owid-grapher,owid/owid-grapher,owid/owid-grapher,owid/owid-grapher