added some progress messages

inventory_provider/tasks/worker.py

@@ -601,10 +601,15 @@ def _build_interface_services(update_callback=lambda s: None):
             return 'lhcone'
         return None
 
-
     r = get_next_redis(InventoryTask.config)
     rp = r.pipeline()
-    for ifc in list(_interfaces()):
+
+    update_callback('loading all known interfaces')
+    interfaces = list(_interfaces())
+    update_callback(f'loaded {len(interfaces)} interfaces, '
+                    'saving by service category')
+
+    for ifc in interfaces:
         service_type = _classify(ifc)
         if not service_type:
             continue