bug(aria/grid): Calculation of roving tabindex includes disabled elements

[aHereitani]

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 using a grid, recalculation of the new tabbable element includes disabled elements. In case the grid property "softDisabled" set to false and the disabled element is chosen, keyboard (arrow-)navigation is broken and no item is reachable by tabbing.
The sample below just disables a Tag in
https://angular.dev/guide/aria/grid#layout-grid

Reproduction

StackBlitz link:
https://stackblitz.com/edit/xxmzuhtu-r15d3sle
Steps to reproduce:

1. delete "Angular" Tag
2. see that the new tabbable element is the disabled delete button making keyboard navigation impossible.

Expected Behavior

Disabled elements should not be considered for the roving tabindex calculation.

Actual Behavior

Disabled elements are considered for the roving tabindex calculation.

Environment

Angular CLI : 22.0.7
Angular : 22.0.7
Node.js : 22.22.3
Package Manager : npm 10.8.2
Operating System : linux x64