bug(form-field): difficult to customize shape with tokens

### 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

19

### Description

When using mat-form-field in filled appearance, I want to shape the border-radius. I use this token
--mdc-filled-text-field-container-shape: 4px !important;
But it only applies to the top corners and not the bottom corners because this token uses the wrong container to set radius. It sets the radius on a level where the div for hints and errors is also included.
And by that the bottom corners are not set with that token

### Reproduction

StackBlitz link:
Steps to reproduce:
1.
2.

### Expected Behavior

Apply radius also to bottom corners

### Actual Behavior

not applying radius to bottom corners

### Environment

- Angular: 19
- CDK/Material: 19
- Browser(s): firefox
- Operating System (e.g. Windows, macOS, Ubuntu): windows

Commencez par examiner l’apparence filled de Angular Material mat-form-field et la manière dont --mdc-filled-text-field-container-shape est appliqué. Reproduisez le style signalé avec Angular 19, puis déterminez quel conteneur possède les coins inférieurs ; le travail est terminé lorsque le token applique systématiquement le rayon demandé à tous les coins, y compris lorsque des aides ou des erreurs sont présents.

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