Remove `facetSpacing`, which is not a valid scale config (#4574)
Remove `facetSpacing`, which is not a valid scale config (#4574)


uwdata/vega-lite,uwdata/vega-lite,vega/vega-lite,uwdata/vega-lite,vega/vega-lite,uwdata/vega-lite,vega/vega-lite,vega/vega-lite,vega/vega-lite,uwdata/vega-lite