bug(mat-button, mat-icon): mat-icon inside of mat-button are truncated

### Is this a regression?

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

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

Not sure which

### Description

Using Angular 19 with angular material, if I put a `mat-icon` element inside of a `mat-button`, the icon is not completely visible. It is truncated a little at its top and bottom. See reproduction StackBlitz below.

### Reproduction

Forked the "Button Angular Component" example to display the problem.

Editor: https://stackblitz.com/edit/3zsvfedr?file=src%2Fexample%2Fbutton-overview-example.html
Application: https://3zsvfedr.stackblitz.io

See the second button in the "Basic" "Raised" "Stroke" and "Flat" table rows.

### Expected Behavior

I would expect the icon to be fully visible, not truncated. In case of the `add_circle` icon, I would expect its shape to be perfectly round.

### Actual Behavior

The top and bottom of the icon are truncated (cropped) which makes it painfully _not round_.


### Environment

- Angular: 19
- CDK/Material: 19.2.7
- Browser(s): Edge, Chrome and Firefox
- Operating System: Windows

リンクされている StackBlitz の再現から始め、Basic、Raised、Stroke、Flat の各例の 2 番目のボタンを比較します。クリッピングに関係する Angular Material の mat-button と mat-icon のレンダリングおよびスタイリングを追跡します。アイコンが完全に表示され、報告されているブラウザー全体で add_circle アイコンが円形に表示されれば完了です。

索引モデルが issue の本文から書いたものです。