Check if reverse proxy is correctly configured (#30890) (#30935)

Backport #30890 by wxiaoguang

Follow #27011
Follow #30885

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>

web_src/js/features/common-global.js

@@ -451,5 +451,5 @@ export function checkAppUrl() {
     return;
   }
   showGlobalErrorMessage(`Your ROOT_URL in app.ini is "${appUrl}", it's unlikely matching the site you are visiting.
-Mismatched ROOT_URL config causes wrong URL links for web UI/mail content/webhook notification/OAuth2 sign-in.`);
+Mismatched ROOT_URL config causes wrong URL links for web UI/mail content/webhook notification/OAuth2 sign-in.`, 'warning');
 }