Add default location for action log archiving

Prevents the logs from being written to the preferred storage, which means they will jump around

workers/logrotateworker.py

@@ -53,7 +53,13 @@ class LogRotateWorker(Worker):
         return
 
   def _perform_archiving(self, cutoff_id):
-    log_archive = DelegateUserfiles(app, storage, SAVE_LOCATION, SAVE_PATH)
+    save_location = SAVE_LOCATION
+    if not save_location:
+      # Pick the *same* save location for all instances. This is a fallback if
+      # a location was not configured.
+      save_location = storage.locations[0]
+
+    log_archive = DelegateUserfiles(app, storage, save_location, SAVE_PATH)
 
     with UseThenDisconnect(app.config):
       start_id = get_stale_logs_start_id()