Moved "Lock databases on screen lock" setting to security settings

widget.
Changed wording and preference variable name for conformity with
existing settings.

src/gui/MainWindow.cpp

@@ -965,7 +965,7 @@ void MainWindow::hideYubiKeyPopup()
 
 void MainWindow::handleScreenLock()
 {
-    if (config()->get("AutoCloseOnScreenLock").toBool()){
+    if (config()->get("security/lockdatabasescreenlock").toBool()){
         lockDatabasesAfterInactivity();
     }
 }