qt: Fix status bar icons ignoring update activity setting.

Disabling status bar icons activity was left unimplemented on qt.
Prevent refreshing the icons and clear their activity status on setting
change.

src/qt/qt_mainwindow.cpp

@@ -2231,6 +2231,9 @@ MainWindow::on_actionUpdate_status_bar_icons_triggered()
 {
     update_icons ^= 1;
     ui->actionUpdate_status_bar_icons->setChecked(update_icons);
+
+    /* Prevent icons staying when disabled during activity. */
+    status->clearActivity();
 }
 
 void