Simplify API query filtering

src/backend/InvenTree/build/api.py

@@ -41,7 +41,7 @@ class BuildFilter(rest_filters.FilterSet):
 
         Note: Also account for the possibility of a custom status code
         """
-        q1 = Q(status=value, status_custom_key__isnull=True)
+        q1 = Q(status=value)
         q2 = Q(status_custom_key=value)
 
         return queryset.filter(q1 | q2).distinct()

src/backend/InvenTree/order/api.py

@@ -86,7 +86,7 @@ class OrderFilter(rest_filters.FilterSet):
 
         Note: Also account for the possibility of a custom status code.
         """
-        q1 = Q(status=value, status_custom_key__isnull=True)
+        q1 = Q(status=value)
         q2 = Q(status_custom_key=value)
 
         return queryset.filter(q1 | q2).distinct()

src/backend/InvenTree/stock/api.py

@@ -575,7 +575,7 @@ class StockFilter(rest_filters.FilterSet):
 
         Note: Also account for the possibility of a custom status code.
         """
-        q1 = Q(status=value, status_custom_key__isnull=True)
+        q1 = Q(status=value)
         q2 = Q(status_custom_key=value)
 
         return queryset.filter(q1 | q2).distinct()