DEV: fix the mobile spec

In discourse/discourse#30242, the topic footer
buttons mobile dropdown can be replaced by the button if there's only
one option.

This fixes the spec that was clicking on the dropdown button before
checking there was no assign option.

test/javascripts/acceptance/assign-disabled-test.js

@@ -1,4 +1,4 @@
-import { click, visit } from "@ember/test-helpers";
+import { visit } from "@ember/test-helpers";
 import { test } from "qunit";
 import { acceptance } from "discourse/tests/helpers/qunit-helpers";
 
@@ -9,7 +9,6 @@ acceptance("Discourse Assign | Assign disabled mobile", function (needs) {
 
   test("Footer dropdown does not contain button", async function (assert) {
     await visit("/t/internationalization-localization/280");
-    await click(".topic-footer-mobile-dropdown-trigger");
     assert.dom(".assign").doesNotExist();
   });
 });