bug(mat-stepper): on iOS device (iphone 15, iOS 18.5), any label or input field in stepper panel gets announced with 'tab' suffix

### 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

unknown

### Description

Hi Team,
We are observing one accessibility issue for mat-stepper on iOS device. The mat-stepper when used on android device or an windows then announces labels correctly. But when it is opened on iOS device, then screen reader read every field in tab panel with suffix 'tab'. Like in provided example for tabpanel in first step, screen reader reads like 'first step, last step tab' then 'next tab'. It doesn't announce 'next button' instead it announce all the elements in tabpanel with suffix tab.

### Reproduction

StackBlitz link: https://stackblitz.com/edit/2webe4ha?file=package.json
Steps to reproduce:
1. Open mat-stepper example on iOS device
2. listen to screen reader announcing the page contents
3. for first step it should announce next button as 'button next' but it announces as 'next tab'

### Expected Behavior

Fields should be properly announced when they are inside mat-stepper panel like for button it should read as 'next button' .

### Actual Behavior

Fields inside mat-stepper panel are getting announced with 'tab' suffix like for next button, it is reading as 'next tab'.

### Environment

- Angular: v20.1.0
- CDK/Material: v20.1.0
- Browser(s):
- Operating System (e.g. Windows, macOS, Ubuntu): iOS device

Beginne mit der verknüpften StackBlitz-Reproduktion und überprüfe das mat-stepper-Beispiel mit Angular/CDK Material v20.1.0 auf einem iOS-Gerät mit aktiviertem Screenreader. Vergleiche die Ansagen für die Beschriftungen, Eingabefelder und die Next-Schaltfläche des Stepper-Panels mit dem Verhalten unter Android oder Windows. Als abgeschlossen gilt die Aufgabe, wenn die Steuerelemente des Panels mit ihren korrekten Rollen und nicht mit dem Suffix „tab“ angesagt werden.

Vom Indexierungsmodell aus dem Issue-Text verfasst.