Fixed review comments for Import/Export Servers.

refs #4803

web/pgadmin/misc/file_manager/static/js/utility.js

@@ -712,7 +712,7 @@ define([
 
     var loading_icon_url = url_for(
       'static', {
-        'filename': 'js/generated/load-root.gif',
+        'filename': 'img/loading.gif',
       }
     );
 

web/pgadmin/misc/file_manager/templates/file_manager/index.html

@@ -58,7 +58,7 @@
     </div>
     <div class="fileinfo flex-grow-1 d-flex">
         <span class="activity">
-        <img src="{{ url_for('static', filename='js/generated/img/load-root.gif') }}"
+        <img src="{{ url_for('static', filename='img/loading.gif') }}"
             alt="{{ _('Loading...') }}">
         </span>
         <div class="file_listing"></div>