Remove fallback loading message in spa.html

Removed fallback loading message from spa.html.

Author: eschutho

superset/templates/superset/spa.html

@@ -102,11 +102,6 @@
             alt="Loading..."
             style="{{ spinner_style }}"
           />
-        {% else %}
-          <!-- Fallback: This should rarely happen with new logic -->
-          <div style="{{ spinner_style }}">
-            Loading...
-          </div>
         {% endif %}
       </div>
     {% endblock %}