refactor: replace username old focus logic with the autofocus attribute (#2223)

frontend/src/views/Login.vue

@@ -6,10 +6,10 @@
       <div v-if="error !== ''" class="wrong">{{ error }}</div>
 
       <input
+        autofocus
         class="input input--block"
         type="text"
         autocapitalize="off"
-        ref="username"
         v-model="username"
         :placeholder="$t('login.username')"
       />
@@ -71,8 +71,6 @@ export default {
     };
   },
   mounted() {
-    this.focusUsername();
-
     if (!recaptcha) return;
 
     window.grecaptcha.ready(function () {
@@ -82,9 +80,6 @@ export default {
     });
   },
   methods: {
-    focusUsername() {
-      this.$refs.username.focus();
-    },
     toggleMode() {
       this.createMode = !this.createMode;
     },