Finalize e2e coverage for the native instrumentation path #21395

Add the remaining e2e coverage for the native instrumentation path to the react-router-7-framework-instrumentation app.

- `db.redis` spans nest under the **native** (instrumentation-API) `http.server` transaction — verifies OTel auto-instrumentation still shares context on the native path.
- Exactly one `http.server` transaction per request (no double-instrumentation).
- Pageload transaction is parameterized for dynamic routes (`/performance/with/:param`).