indexer-storage: Update configuration structure

docker/conf/indexer.yml

@@ -8,8 +8,7 @@ objstorage:
     url: http://swh-objstorage:5003/
 indexer_storage:
   cls: remote
-  args:
-    url: http://swh-idx-storage:5007/
+  url: http://swh-idx-storage:5007/
 scheduler:
   cls: remote
   args:

docker/conf/indexer_storage.yml

 indexer_storage:
   cls: local
-  args:
-    db: postgresql:///?service=swh-indexers
+  db: postgresql:///?service=swh-indexers