bug(matMenuTriggerFor): nested menu element is activated right away if it appears above its trigger

### 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

When a nested menu element appears above its trigger `mat-menu-item` it is activated right away.

### Reproduction

StackBlitz link: https://stackblitz.com/run?file=src%2Fapp%2Fmenu-nested-example.ts
Steps to reproduce:
1. Make the window small enough for the nested menu to appear above the trigger (e.g. using chrome dev tools).
2. Tap (!) the menu trigger

### Expected Behavior

The menu is opened, but the item is not activated

### Actual Behavior

The menu is opened, but closed right away with the item below the cursor activated

### Environment

- Angular: 19 (happens in earlier versions too)
- CDK/Material: 19
- Browser(s):
- Operating System (e.g. Windows, macOS, Ubuntu):
all of them

Beginne mit der StackBlitz-Reproduktion in src/app/menu-nested-example.ts und mache das Fenster klein genug, damit das verschachtelte Menü oberhalb seines Auslösers erscheint. Tippe auf den Auslöser und überprüfe, dass sich das Menü öffnet, ohne sich sofort wieder zu schließen oder das Element unter dem Cursor zu aktivieren; der Fix sollte das erwartete Verhalten über die gemeldeten Angular- und CDK/Material-Versionen hinweg beibehalten.

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