bug(Material 3 > Button): When button is last child element in mat-dialog-content it causes a vertical scrollbar to appear

### 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

v17 (Material 2)

### Description

When button is last child element in mat-dialog-content it causes a vertical scrollbar to appear.

### Reproduction

StackBlitz [link](https://stackblitz.com/edit/stackblitz-starters-1giu8v?file=src%2Fapp%2Fdialog%2Fdialog.component.html)
Steps to reproduce:
1. Create Angular v18 project + add Angular material v18
2. Create a dialog component
3. In dialog component: Add a mat-button in mat-dialog-content
4. Open dialog


### Expected Behavior

There should be no vertical scrollbar in the dialog

### Actual Behavior

There is a vertical scroll bar in the dialog

### Environment

- Angular: "@angular/core": "18.0.0"
- CDK/Material: "@angular/material": "18.0.0"
- Browser(s): Edge
- Operating System: Windows

Angular CLI: 18.0.0
Node: 22.2.0
Package Manager: npm 10.7.0
OS: win32 x64

Angular: 18.0.0
... animations, cdk, cli, common, compiler, compiler-cli, core
... forms, language-service, material, material-luxon-adapter
... platform-browser, platform-browser-dynamic, platform-server
... router

Package Version
---------------------------------------------------------
@angular-devkit/architect 0.1800.0
@angular-devkit/build-angular 18.0.0
@angular-devkit/core 18.0.0
@angular-devkit/schematics 18.0.0
@schematics/angular 18.0.0
rxjs 7.8.1
typescript 5.4.5
zone.js 0.14.6

Start with the linked StackBlitz reproduction and verify the scrollbar in an Angular 18 Material dialog containing a button as the last child of mat-dialog-content. Trace the dialog-content and Material button styles involved; done means the reproduced dialog has no unwanted vertical scrollbar while retaining expected scrolling for overflowing content.

Written by the indexing model from the issue text.