Bring back demo login info

src/oidcserver.js

@@ -296,7 +296,7 @@ async function renderInteractionPage(req, res, next) {
             ICON_URL: '/api/v1/cloudron/avatar',
             NAME: client.name || await branding.getCloudronName(),
             FOOTER: marked.parse(await branding.renderFooter()),
-            NOTE: (client.id === oidcClients.ID_WEBADMIN && constants.DEMO) ? '<div style="text-align: center;">This is a demo. Username and password is "cloudron"</div>' : ''
+            NOTE: constants.DEMO ? `This is a demo. Username and password is "${constants.DEMO_USERNAME}"` : '',
         };
 
         if (app) {