#86 District column simplification

* simplifies the fetching of districts for district column

ema/tables.py

@@ -103,9 +103,7 @@ class EmaTable(BaseTable, TableRenderMixin):
         Returns:
 
         """
-        parcels = value.parcels.filter(
-            parcelintersection__calculated_on__isnull=False,
-        ).values_list(
+        parcels = value.get_underlying_parcels().values_list(
             "gmrkng",
             flat=True
         ).distinct()