bug(dialog): usage of MAT_DIALOG_DEFAULT_OPTIONS resets default options

### 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 is either a documentation issue or an issue with the behaviour of `MAT_DIALOG_DEFAULT_OPTIONS`.

When specifying
```js
{
provide: MAT_DIALOG_DEFAULT_OPTIONS,
useValue: {
panelClass: 'mat-field-inside-dialog-workaround',
} as MatDialogConfig
}
```

The `autoFocus` of dialogs gets disabled, this is unexpected as the developer never stated it to be disabled and [the documentation states](https://material.angular.io/components/dialog/overview#focus-management):
> When opened, MatDialog traps browser focus such that it cannot escape the root role="dialog" element. **By default, the first tabbable element in the dialog receives focus.** You can customize which element receives focus with the autoFocus property of MatDialogConfig, which supports the following values.

###

### Reproduction

StackBlitz link: https://stackblitz.com/edit/kxsrvy?file=src%2Fexample%2Fdialog-overview-example.ts
Steps to reproduce:
1. Open Dialog
2. There is no focus set on the input
3. Comment out the `MAT_DIALOG_DEFAULT_OPTIONS ` in `main.ts`.
1. Open Dialog
2. There **is** focus set on the input

### Expected Behavior

The default should be kept,

Otherwise the documentation should be revised that overwriting another property can change others.

### Actual Behavior

Overwriting one property of `MatDialogConfig` in `MAT_DIALOG_DEFAULT_OPTIONS` changes the default behaviour of unrelated (not overwritten properties).

### Environment

- Angular: 16.2.5
- CDK/Material: 16.2.12
- Browser(s): Edge
- Operating System (e.g. Windows, macOS, Ubuntu): Windows 11

Commencez par la reproduction StackBlitz et examinez le provider MAT_DIALOG_DEFAULT_OPTIONS dans main.ts. Comparez le comportement de focus observé avec la documentation sur la gestion du focus des dialogs et déterminez si le problème vient du comportement ou de la documentation. C’est terminé lorsque la reproduction et le comportement de focus par défaut attendu sont réconciliés.

Rédigé par le modèle d'indexation à partir du texte de l'issue.