[Bug]: Spector large LRO header returns malformed initial response

### Describe the bug

Added in https://github.com/Azure/typespec-azure/pull/2677

Per the design guidelines, the initial response must return a status monitor.

The absence of the status monitor breaks SDKs that provide it to callers (Rust).

### Reproduction

Inspect https://github.com/Azure/typespec-azure/blob/main/packages/azure-http-specs/specs/azure/resource-manager/large-header/mockapi.ts#L19-L50 to see lack of status monitor.

### Checklist

- [x] Follow our [Code of Conduct](https://github.com/azure/typespec-azure/blob/main/CODE_OF_CONDUCT.md)
- [x] Check that this issue is about the Azure libraries for typespec. For bug in the typespec language or core libraries file it in the [TypeSpec repo](https://github.com/Microsoft/TypeSpec/issues/new/choose)
- [x] Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
- [x] The provided reproduction is a [minimal reproducible example](https://stackoverflow.com/help/minimal-reproducible-example) of the bug.

Inspect packages/azure-http-specs/specs/azure/resource-manager/large-header/mockapi.ts at lines 19-50 and compare the initial response with the applicable design guidelines. Verify the large-header mock API response exposes a status monitor so SDKs, including Rust, can provide it to callers.

Written by the indexing model from the issue text.