fix: update metadata base URL retrieval logic (assistant-ui#2977)

Author: petekp

apps/docs/app/layout.tsx

@@ -7,14 +7,6 @@ import { Provider } from "./provider";
 import { cn } from "@/lib/utils";
 
 const getMetadataBase = () => {
-  const appUrl = process.env["NEXT_PUBLIC_APP_URL"];
-  if (appUrl) {
-    return new URL(appUrl);
-  }
-  const vercelUrl = process.env["VERCEL_URL"];
-  if (vercelUrl) {
-    return new URL(`https://${vercelUrl}`);
-  }
   if (process.env.NODE_ENV === "production") {
     return new URL("https://www.assistant-ui.com");
   }