FIX: Ensure poll type toggle buttons function correctly (#18540)

Followup to 03b7b7d1bc

plugins/poll/assets/javascripts/controllers/poll-ui-builder.js

@@ -402,6 +402,6 @@ export default Controller.extend(ModalFunctionality, {
   @action
   updatePollType(pollType, event) {
     event?.preventDefault();
-    this.pollType = pollType;
+    this.set("pollType", pollType);
   },
 });

plugins/poll/assets/javascripts/discourse/templates/modal/poll-ui-builder.hbs

@@ -1,15 +1,15 @@
 <DModalBody @title="poll.ui_builder.title" @class="poll-ui-builder">
   <div class="input-group poll-type">
-    <a href {{on "click" (fn this.updatePollType "regular")}} class="poll-type-value {{if this.isRegular "active"}}">
+    <a href {{on "click" (fn this.updatePollType "regular")}} class="poll-type-value poll-type-value-regular {{if this.isRegular "active"}}">
       {{i18n "poll.ui_builder.poll_type.regular"}}
     </a>
 
-    <a href {{on "click" (fn this.updatePollType "multiple")}} class="poll-type-value {{if this.isMultiple "active"}}">
+    <a href {{on "click" (fn this.updatePollType "multiple")}} class="poll-type-value poll-type-value-multiple {{if this.isMultiple "active"}}">
       {{i18n "poll.ui_builder.poll_type.multiple"}}
     </a>
 
     {{#if this.showNumber}}
-      <a href {{on "click" (fn this.updatePollType "number")}} class="poll-type-value {{if this.isNumber "active"}}">
+      <a href {{on "click" (fn this.updatePollType "number")}} class="poll-type-value poll-type-value-number {{if this.isNumber "active"}}">
         {{i18n "poll.ui_builder.poll_type.number"}}
       </a>
     {{/if}}

plugins/poll/test/javascripts/acceptance/poll-builder-enabled-test.js

@@ -3,6 +3,7 @@ import {
   exists,
   updateCurrentUser,
 } from "discourse/tests/helpers/qunit-helpers";
+import { click } from "@ember/test-helpers";
 import { clearPopupMenuOptionsCallback } from "discourse/controllers/composer";
 import { displayPollBuilderButton } from "discourse/plugins/poll/helpers/display-poll-builder-button";
 import { test } from "qunit";
@@ -24,6 +25,22 @@ acceptance("Poll Builder - polls are enabled", function (needs) {
       exists(".select-kit-row[data-value='showPollBuilder']"),
       "it shows the builder button"
     );
+
+    await click(".select-kit-row[data-value='showPollBuilder']");
+    assert.true(
+      exists(".poll-type-value-regular.active"),
+      "regular type is active"
+    );
+    await click(".poll-type-value-multiple");
+    assert.true(
+      exists(".poll-type-value-multiple.active"),
+      "multiple type is active"
+    );
+    await click(".poll-type-value-regular");
+    assert.true(
+      exists(".poll-type-value-regular.active"),
+      "regular type is active"
+    );
   });
 
   test("regular user - insufficient trust level", async function (assert) {