ui: use Async tools from widget toolkit

The api2 one passes the whole response (for more flexibility) on
reject, so we need to adapt to that.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

www/config/TfaView.js

@@ -161,14 +161,14 @@ Ext.define('PBS.config.TfaView', {
 
 	    try {
 		me.getView().mask(gettext('Please wait...'), 'x-mask-loading');
-		await PBS.Async.api2({
+		await Proxmox.Async.api2({
 		    url: `/api2/extjs/access/tfa/${record.id}`,
 		    method: 'DELETE',
 		    params,
 		});
 		me.reload();
-	    } catch (error) {
-		Ext.Msg.alert(gettext('Error'), error);
+	    } catch (response) {
+		Ext.Msg.alert(gettext('Error'), response.result.message);
 	    } finally {
 		me.getView().unmask();
             }