Essentially #1723 (reduce surface tag precision in roads layer, but for landuse layer.

We're adding even more landcover polygons via #1259. We should endever to not increase the file size a huge amount.

I propose this simplification start be zooms 0 to 12 inclusive (so zoom 13 would have the "raw" values). This also corresponds roughly with where raster landcover sources max out on their spatial fidelity.

Related:

• ☂ Reduce landuse layer size at mid-zooms #1721 to reduce landuse size at mid-zooms
• More id dropping at low zooms (landuse) #1033 to drop IDs at low zooms in landuse layer