Remove username check from submit handler

ee/app/assets/javascripts/arkose_labs/components/sign_in_arkose_app.vue

@@ -88,8 +88,7 @@ export default {
     onUsernameBlur() {
       this.username = this.getUsernameValue();
     },
-    async onSubmit(e) {
-      await this.checkIfNeedsChallenge();
+    onSubmit(e) {
       if (!this.arkoseInitialized || this.arkoseChallengePassed) {
         return;
       }