UX: Remove flat icons from wizard step two (#30761)

### What's changed?
This PR removes the flat icons from wizard step 2, as they are not used
elsewhere in the wizard. Keeping the steps consistent with the existing
style improves visual alignment and avoids unnecessary elements.

### Before
<img width="511" alt="image"
src="https://github.com/user-attachments/assets/9e8b6f46-7c35-433b-9f5e-511579bc4768"
/>


### After
<img width="514" alt="image"
src="https://github.com/user-attachments/assets/028e52af-9777-4733-8ff4-1daab5b39e22"
/>

app/assets/javascripts/discourse/app/static/wizard/components/fields/radio.gjs

@@ -4,7 +4,6 @@ import { on } from "@ember/modifier";
 import { action, set } from "@ember/object";
 import PluginOutlet from "discourse/components/plugin-outlet";
 import concatClass from "discourse/helpers/concat-class";
-import icon from "discourse/helpers/d-icon";
 import withEventValue from "discourse/helpers/with-event-value";
 
 export default class Radio extends Component {
@@ -54,9 +53,6 @@ export default class Radio extends Component {
                 {{on "change" (withEventValue this.selectionChanged)}}
               />
               <span class="wizard-container__radio-label">
-                {{#if choice.icon}}
-                  {{icon choice.icon}}
-                {{/if}}
                 <span>{{choice.label}}</span>
               </span>
             </PluginOutlet>

lib/wizard/builder.rb

@@ -90,8 +90,8 @@ class Wizard
           type: "radio",
           value: SiteSetting.invite_only ? "invite_only" : "sign_up",
         ) do |field|
-          field.add_choice("sign_up", icon: "user-plus")
-          field.add_choice("invite_only", icon: "paper-plane")
+          field.add_choice("sign_up")
+          field.add_choice("invite_only")
         end
 
         step.add_field(