Use the overridable get_default_farm when starting S3 imports

Closes #1727 (closed)

Fixing the expected failures on starting processes with farms could have allowed us to catch this. I added some new tests with mocks to check that the correct get_default_farm is called, and opened https://redmine.teklia.com/issues/7025 to deal with all the other expected failures.

arkindex/documents/serializers/entities.py

@@ -31,7 +31,7 @@ class EntityTypeSerializer(serializers.ModelSerializer):
         # Get an error if a request tries to change an entity type's corpus
         corpus = data.get("corpus")
         if self.instance and corpus:
-            raise ValidationError({"corpus": ["It is not possible to update an Entity Type\'s corpus."]})
+            raise ValidationError({"corpus": ["It is not possible to update an Entity Type's corpus."]})
         data = super().to_internal_value(data)
         return data