docs(core): remove usage notes from ReflexiveInjector.parent property (#26039)

Properties are not allowed usage notes, and in this case the example
is so simple it didn't warrant moving it to the overall class documentation.

PR Close #26039

packages/core/src/di/reflective_injector.ts

@@ -153,15 +153,6 @@ export abstract class ReflectiveInjector implements Injector {
    *
    * <!-- TODO: Add a link to the section of the user guide talking about hierarchical injection.
    * -->
-   *
-   * @usageNotes
-   * ### Example
-   *
-   * ```typescript
-   * var parent = ReflectiveInjector.resolveAndCreate([]);
-   * var child = parent.resolveAndCreateChild([]);
-   * expect(child.parent).toBe(parent);
-   * ```
    */
   abstract get parent(): Injector|null;