fix the url in the service not available error

packages/firebase_vertexai/firebase_vertexai/lib/src/error.dart

@@ -56,12 +56,16 @@ final class ServiceApiNotEnabled implements VertexAIException {
       'The Vertex AI in Firebase SDK requires the Vertex AI in Firebase API '
       '(`firebasevertexai.googleapis.com`) to be enabled in your Firebase project. Enable this API '
       'by visiting the Firebase Console at '
-      'https://console.firebase.google.com/$_projectId/genai '
+      'https://console.firebase.google.com/project/${_getID()}/genai '
       'and clicking "Get started". If you enabled this API recently, wait a few minutes for the '
       'action to propagate to our systems and then retry.';
 
   @override
   String toString() => message;
+
+  String _getID() {
+    return _projectId.replaceAll('projects/', '');
+  }
 }
 
 /// Exception thrown when the quota is exceeded.