feat(tdx_google): add onFailure action to reboot on metadata.service errors

- Introduce `onFailure` handler to trigger reboot after 5 minutes.
- Enhances system reliability by automating recovery measures.

Signed-off-by: Harald Hoyer <harald@matterlabs.dev>

packages/tdx_google/metadata.nix

@@ -49,5 +49,8 @@
       KAFKA_URLS="''${KAFKA_URLS}"
       EOF
     '';
+    postStop = lib.mkDefault ''
+      shutdown --reboot +5
+    '';
   };
 }