bug(chips): Arrows navigation in NVDA browse mode automatically switched to focus mode (again)

### 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

This pretty much the same bug as https://github.com/angular/components/issues/20761

### Reproduction

Steps to reproduce:
1. Go to https://material.angular.dev/components/chips/examples
2. Open NVDA screen reader in browse mode
3. Start navigating in browse mode with a help of up/down arrows
4. Navigate with the help of arrows to chips select list

### Expected Behavior

NVDA is reading information about the select list and keeps navigating in the browse mode

### Actual Behavior

NVDA automatically switches to the focus mode and prevents user from further page exploring in the browse mode.

### Environment

- Angular: 20.2
- CDK/Material: Material components
- Browser(s): Chrome
- Operating System (e.g. Windows, macOS, Ubuntu): Windows
- NVDA 2025.3

まず、Chrome、NVDA 2025.3、および記載されているブラウズモードでの手順を使って、Material chips の examples ページで問題を再現します。次に、これまでのコンテキストについて関連する issue #20761 を確認し、その後、chips の select list に移動しても NVDA がブラウズモードのままで、select list の情報を引き続き読み上げることを確認します。

索引モデルが issue の本文から書いたものです。