remove username/password banner

Author: hay-kot

frontend/layouts/blank.vue

@@ -5,8 +5,6 @@
     <v-banner v-if="isDemo" sticky>
       <div class="text-center">
         <b> {{ $t("demo.info_message_with_version", { version: version }) }} </b> |
-        {{ $t("demo.demo_username", { username: "changeme@example.com" }) }} |
-        {{ $t("demo.demo_password", { password: "demo" }) }}
       </div>
     </v-banner>