qt: MyTreeView.refresh_all to use maybe_defer_update

In particular, window.timer_actions() calls
request_list.refresh_all() and invoice_list.refresh_all(),
every 0.5 seconds.
We avoid doing this at least when those lists are not visible anyway.

electrum/gui/qt/util.py

@@ -813,6 +813,8 @@ class MyTreeView(QTreeView):
                 return row
 
     def refresh_all(self):
+        if self.maybe_defer_update():
+            return
         for row in range(0, self.std_model.rowCount()):
             item = self.std_model.item(row, 0)
             key = item.data(self.key_role)