Feature Request: Track deleted objects in inventory

### Checklist

- [x] I did not find a related open enhancement request.
- [x] I understand that enhancement requests filed in the GitHub repository are by default low priority.
- [x] If this request is time-sensitive, I have submitted a corresponding issue with [GCP support](https://cloud.google.com/support-hub).

### Describe the feature

Currently, Config Sync removes objects from its inventory immediately upon deletion, losing track of them even if they remain stuck in a "Terminating" state on the cluster. We should enhance the user experience by maintaining visibility and tracking for these objects until they are fully pruned from the cluster, ensuring the inventory accurately reflects the live state.

### Importance

_No response_