Re-enable Issue2954 test on iOS/Catalyst - TableView cell becomes empty after adding with context actions

The test for issue #2954 is currently completely disabled on iOS and Catalyst platforms. The issue is related to TableView cells becoming empty after adding a new cell with context actions.

## Current State

The entire test file is wrapped in a conditional compilation directive:

```csharp
#if TEST_FAILS_ON_IOS && TEST_FAILS_ON_CATALYST
// ... entire test ...
#endif
```

This means the test never runs on iOS or Catalyst.

## Test File
- `src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/XFIssue/Issue2954.cs`

## Related Issues
- Original issue logged: #26091

## Test Details

**Issue**: Cell becomes empty after adding a new one with context actions (TableView)

**Test scenario**:
1. Wait for "Cell2" element
2. Tap "Add new" button
3. Verify "Cell2" is still visible

## Expected Behavior

After adding a new TableView cell with context actions, existing cells should remain visible and not become empty.

## Acceptance Criteria

- [ ] Investigate the root cause of the cell visibility issue on iOS/Catalyst
- [ ] Fix the underlying platform issue
- [ ] Remove the `#if TEST_FAILS_ON_IOS && TEST_FAILS_ON_CATALYST` wrapper
- [ ] Verify test passes on iOS and Catalyst platforms

Start with src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/XFIssue/Issue2954.cs and inspect the conditional compilation wrapper and the Cell2/Add new scenario. Reproduce the test on iOS and Catalyst, investigate why the existing TableView cell becomes empty, and verify the test passes on both platforms after the underlying issue is fixed and the wrapper is removed.

Written by the indexing model from the issue text.