refactor(@schematics/angular): Remove zoneless prompt

Remove the zoneless prompt altogether in v21. Zoneless is the default experience.

fixes angular#30531

Author: atscott

packages/schematics/angular/application/schema.json

@@ -124,7 +124,6 @@
     },
     "zoneless": {
       "description": "Generate an application that does not use `zone.js`.",
-      "x-prompt": "Do you want to create a 'zoneless' application without zone.js?",
       "type": "boolean",
       "default": true
     },