bug(MatInputTestHarness): setValue does not trigger "change" event

### Is this a regression?

- [ ] Yes, this behavior used to work in the previous version

### The previous version in which this bug was not present was

_No response_

### Description

According to the documentation, the MatInput component emits a "change" event when the value changes. However, the test harness does not emit this event after "setValue()". See the stackblitz.

I have tried using focus() to focus the component before setting the value, then blur() to remove focus, which is what triggers "change" in the application, and there is still no "change" event.

### Reproduction

StackBlitz link: https://stackblitz.com/edit/phfedq5f?file=src%2Fexample%2Finput-harness-example.html
Steps to reproduce:
1. modified example test from https://material.angular.io/components/input/examples should run automatically
2. two tests fail because the event spy is not called

### Expected Behavior

You should be able to trigger the expected event with the test harness.

### Actual Behavior

Expected code associated with (change) to run.

### Environment

- Angular: 19
- CDK/Material: 19
- Browser(s): chrome
- Operating System (e.g. Windows, macOS, Ubuntu): Windows, macOs

issue に記載されている MatInputTestHarness の動作から始め、変更された Material input の例に基づく、リンク先の StackBlitz の再現を実行します。focus と blur の試行を含め、setValue() 周辺で失敗しているイベントスパイを確認します。期待される change handler が実行され、再現テストの両方がパスすれば完了です。

索引モデルが issue の本文から書いたものです。