[Sentry] Error: No metadata found for 'contractBalances'

### What is this about?

> [!IMPORTANT]
> See https://github.com/MetaMask/core/issues/5545

Sentry error event: [No metadata found for 'contractBalances'](https://metamask.sentry.io/issues/6621422532/events/a2ce53be23d74a488dfefc254b9a256f/)

```
Error: No metadata found for 'contractBalances'
at anonymous(app:///index.android.bundle:1:9222185)
at reduce(native)
at deriveStateFromMetadata(app:///index.android.bundle:1:9222088)
at getPersistentState(app:///index.android.bundle:1:9222023)
at anonymous(app:///index.android.bundle:1:9218971)
at _in(app:///index.android.bundle:1:9127435)
at anonymous(app:///index.android.bundle:1:9121961)
at reduce(native)
at processNextKey(app:///index.android.bundle:1:9121828)
at apply(native)
at anonymous(app:///index.android.bundle:1:461022)
at _callTimer(app:///index.android.bundle:1:460119)
at callTimers(app:///index.android.bundle:1:461924)
at apply(native)
at __callFunction(app:///index.android.bundle:1:347004)
at anonymous(app:///index.android.bundle:1:345336)
at __guard(app:///index.android.bundle:1:346291)
at callFunctionReturnFlushedQueue(app:///index.android.bundle:1:345294)

```

### Scenario

_No response_

### Design

_No response_

### Technical Details

_No response_

### Threat Modeling Framework

_No response_

### Acceptance Criteria

_No response_

### Stakeholder review needed before the work gets merged

- [ ] Engineering (needed in most cases)
- [ ] Design
- [ ] Product
- [ ] QA (automation tests are required to pass before merging PRs but not all changes are covered by automation tests - please review if QA is needed beyond automation tests)
- [ ] Security
- [ ] Legal
- [ ] Marketing
- [ ] Management (please specify)
- [ ] Other (please specify)

### References

_No response_

Start with the linked MetaMask/core issue and search the mobile codebase for `contractBalances`, `deriveStateFromMetadata`, and `getPersistentState`, which appear in the Sentry stack trace. Determine why metadata is missing for this key and verify that the Sentry error no longer occurs; the issue provides no named file, test, or acceptance criteria.

Written by the indexing model from the issue text.