have instances be filtered by ID in case of no filtering criteria passed in

and then switch from using order by ID as a fallback for all ordering and instead
just set instances ordering to ID as default to prevent
OrderedManyToMany fields ordering from being interrupted.

awx/api/views/__init__.py

@@ -365,6 +365,7 @@ class InstanceList(ListAPIView):
     model = models.Instance
     serializer_class = serializers.InstanceSerializer
     search_fields = ('hostname',)
+    ordering = ('id',)
 
 
 class InstanceDetail(RetrieveUpdateAPIView):