docs: decouple selection from aria toolbar examples and guide - #70516

The disabled toolbar example marks its alignment radio group `disabled`.
Toolbars are soft-disabled by default, so the widgets only receive
`aria-disabled` and stay clickable, which the guide describes as focusable
but unavailable.

Since #70516 moved selection into the app, each radio also carries a
`(click)="alignment.set(...)"` handler that never checks the disabled state.
Clicking a disabled radio therefore changes the selection. Before that change
the radios had no app listener and the library ignored clicks on disabled
items.

Drop the three click handlers from the permanently disabled group in the
basic, material and retro variants, the same way the disabled redo button in
the same template already has none.