filter by vector time layers is not working when haystack is enabled.

as for vector_time layer, 'vectorTimeSeries' is indexed instead of 'vector_time'

geonode/layers/search_indexes.py

@@ -97,7 +97,7 @@ def prepare_type(self, obj):
     def prepare_subtype(self, obj):
         if obj.storeType == "dataStore":
             if obj.has_time:
-                return "vectorTimeSeries"
+                return "vector_time"
             else:
                 return "vector"
         elif obj.storeType == "coverageStore":