App Check 'Missing appcheck token' error when performing RTDB operations

- Admin SDK should bypass AppCheck token verifications for RTDB operations. This seems to be a regression issue in `@firebase/database@0.13.0` and up (which is a transitive dependency of `@firebase/database-compat`).
- It appears that the issue was previously fixed in https://github.com/firebase/firebase-js-sdk/pull/5146/files

Can reproduce on `firebase-admin@10.3.0` and up.

```
└─┬ firebase-admin@10.3.0
└─┬ @firebase/database-compat@0.2.2
└── @firebase/database@0.13.2
```

Internal issue: b/236414557