bug(cdkDrag): "pointerPosition" property of the "CdkDragMove" event is not correct with "cdkDragBoundary"

### 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

**Context**
According to the official documentation, the property "pointerPosition" of the "CdkDragMove" event is : "Position of the user's pointer on the page."
See : https://material.angular.io/cdk/drag-drop/api#CdkDragMove

**Problem**
If I use the "cdkDragBoundary" property, the property "pointerPosition" returns cursor position only between boundaries.

### Reproduction

StackBlitz link: https://stackblitz.com/edit/stackblitz-starters-knrvcz?file=src%2Fmain.ts
Steps to reproduce:
1. Move the red block until the cursor moves out of the blue block
2. At the bottom of the blue box, you will see that the cursor position is stuck to the boundaries of the blue box.

### Expected Behavior

I expect to have the current position of the cursor on screen, wherever it is located.

### Actual Behavior

The position displayed of the cursor is limited to the limits of the blue block

### Environment

- Angular: 18.2.8
- CDK/Material: 18.2.8
- Browser(s): Chrome 129.0.6668.100
- Operating System (e.g. Windows, macOS, Ubuntu): Windows 11

Comienza con la reproducción enlazada de StackBlitz en src/main.ts y compara el comportamiento documentado de pointerPosition de CdkDragMove con el resultado cuando cdkDragBoundary está presente. Sigue el manejo de arrastre de CDK que produce el evento y, a continuación, verifica que pointerPosition siga siendo la posición en pantalla del cursor fuera del límite, mientras el elemento arrastrado permanece restringido.

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