remove arealstatistik layers, they have selectbyrectangle=false in the

Select by rectangle can be deactivated for certain layers with the bod property bod.re3.layers_js.selectbyrectangle (true|false). If this attribute is set to false, no sphinx indexes have to be created. Change has been deployed in application code https://github.com/geoadmin/mf-geoadmin3/pull/1435
This pull request is removing the following indices:
* ch.bfs.arealstatistik
* ch.bfs.arealstatistik-1985
* ch.bfs.arealstatistik-1997
* ch.bfs.arealstatistik-bodenbedeckung
* ch.bfs.arealstatistik-bodenbedeckung-1985
* ch.bfs.arealstatistik-bodenbedeckung-1997
* ch.bfs.arealstatistik-bodennutzung
* ch.bfs.arealstatistik-bodennutzung-1985
* ch.bfs.arealstatistik-bodennutzung-1997
* ch.bfs.arealstatistik-hintergrund
* ch.bfs.arealstatistik-waldmischungsgrad