[Bug]: `/health/check` and other subpaths return 400 instead of 404

Requesting subpaths like `/health/check` or `/health/health` returns **400 Bad Request** with a REST controller error instead of **404 Not Found**.

## Expected

```
GET /health/check → 404 Not Found
GET /health/health → 404 Not Found
```

## Actual

```
GET /health/check → 400 Bad Request
Body: {"error":{"code":"BadRequest","message":"Invalid Path for route: health/check.","status":400}}
```

These requests fall through to the REST controller's catch-all route, which tries to interpret `health/check` as an entity path. The error logs show `DataApiBuilderException: Invalid Path for route: health/check`.