component AP gateway: fix bad use of parseAPURL return data:

`parent_item_id` was not retrieved correctly, probably due to a missed update after code
change.

sat/plugins/plugin_comp_ap_gateway/__init__.py

@@ -2365,7 +2365,7 @@ class APGateway:
             )
             return
         try:
-            parent_item_account, parent_item_id = url_args[0].split("/", 1)
+            parent_item_account, parent_item_id = url_args[0], '/'.join(url_args[1:])
         except (IndexError, ValueError):
             log.warning(
                 "Ignoring AP item replying to an XMPP item with invalid inReplyTo URL "