Rename "parents" methods to "ancestors"

Resolves: https://github.com/alphagov/notifications-admin/pull/3980#discussion_r694002952

A grandparent is not a parent, so the return value of these methods
were misleading. This makes it clearer.

app/broadcast_areas/models.py

@@ -124,11 +124,11 @@ class BroadcastArea(BaseBroadcastArea, SortableMixin):
         return self._count_of_phones or 0
 
     @cached_property
-    def parents(self):
-        return list(self._parents_iterator)
+    def ancestors(self):
+        return list(self._ancestors_iterator)
 
     @property
-    def _parents_iterator(self):
+    def _ancestors_iterator(self):
         id = self.id
 
         while True:
@@ -138,9 +138,7 @@ class BroadcastArea(BaseBroadcastArea, SortableMixin):
                 return
 
             parent_broadcast_area = BroadcastArea(parent)
-
             yield parent_broadcast_area
-
             id = parent_broadcast_area.id
 
 

app/models/broadcast_message.py

@@ -104,14 +104,14 @@ class BroadcastMessage(JSONModel):
         )
 
     @property
-    def parent_areas(self):
-        return sorted(set(self._parent_areas_iterator))
+    def ancestor_areas(self):
+        return sorted(set(self._ancestor_areas_iterator))
 
     @property
-    def _parent_areas_iterator(self):
+    def _ancestor_areas_iterator(self):
         for area in self.areas:
-            for parent in area.parents:
-                yield parent
+            for ancestor in area.ancestors:
+                yield ancestor
 
     @cached_property
     def polygons(self):

app/templates/views/broadcast/libraries.html

@@ -14,7 +14,7 @@
 
   {{ page_header("Choose where to send this alert") }}
 
-  {% for area in broadcast_message.parent_areas %}
+  {% for area in broadcast_message.ancestor_areas %}
     <a class="govuk-heading-m govuk-link govuk-link--no-visited-state" href="{{ url_for('.choose_broadcast_sub_area', service_id=current_service.id, broadcast_message_id=broadcast_message.id, library_slug=area.library_id, area_slug=area.id) }}">{{ area.name }}</a>
     {% if loop.last %}
       <div class="keyline-block"></div>