DEV: Fix some more flaky tests (#9384)

Includes:
* DEV: Don't overwrite a computed property in test

test/javascripts/acceptance/emoji-picker-test.js

@@ -3,6 +3,10 @@ import { IMAGE_VERSION as v } from "pretty-text/emoji/version";
 
 acceptance("EmojiPicker", {
   loggedIn: true,
+  beforeEach() {
+    const store = Discourse.__container__.lookup("service:emoji-store");
+    store.reset();
+  },
   afterEach() {
     const store = Discourse.__container__.lookup("service:emoji-store");
     store.reset();