Fixed #35798, Refs #31641 -- Prevented admin navigation sidebar loading flicker.

Thank you to Mario Munoz and Thibaud Colas for the testing and review.

django/contrib/admin/templates/admin/base.html

@@ -10,7 +10,6 @@
 {% endblock %}
 {% if not is_popup and is_nav_sidebar_enabled %}
   <link rel="stylesheet" href="{% static "admin/css/nav_sidebar.css" %}">
-  <script src="{% static 'admin/js/nav_sidebar.js' %}" defer></script>
 {% endif %}
 {% block extrastyle %}{% endblock %}
 {% if LANGUAGE_BIDI %}<link rel="stylesheet" href="{% block stylesheet_rtl %}{% static "admin/css/rtl.css" %}{% endblock %}">{% endif %}

django/contrib/admin/templates/admin/nav_sidebar.html

@@ -1,4 +1,4 @@
-{% load i18n %}
+{% load i18n static %}
 <button class="sticky toggle-nav-sidebar" id="toggle-nav-sidebar" aria-label="{% translate 'Toggle navigation' %}"></button>
 <nav class="sticky" id="nav-sidebar" aria-label="{% translate 'Sidebar' %}">
   <input type="search" id="nav-filter"
@@ -6,3 +6,4 @@
          aria-label="{% translate 'Filter navigation items' %}">
   {% include 'admin/app_list.html' with app_list=available_apps show_changelinks=False %}
 </nav>
+<script src="{% static 'admin/js/nav_sidebar.js' %}"></script>