Reorder POI data update and trigger creation to avoid refresh of materialized view on initial import (#780)

Reorder POI data update and trigger creation to avoid refresh of materialized view after update done by initial import.

I checked the other updates and there are OK.

layers/poi/poi_stop_agg.sql

@@ -33,6 +33,3 @@ CREATE MATERIALIZED VIEW osm_poi_stop_rank AS (
 		subclass IN ('bus_stop', 'bus_station', 'tram_stop', 'subway')
 	ORDER BY p.uic_ref, rk
 ) /* DELAY_MATERIALIZED_VIEW_CREATION */;
-
-ALTER TABLE osm_poi_point ADD COLUMN IF NOT EXISTS agg_stop INTEGER DEFAULT NULL;
-SELECT update_osm_poi_point_agg();