[Backport 10.2] ResourceServlet for skin, angular and ckeditor by default sets wrong cache headers

By default, the SkinResourceServlet, CKEditorResourceServlet and AngularResourceServlet have in the web.xml the following:

<init-param>
      <!--
        Cache timeout in seconds. Make sure to increase it in production environments,
        for example to one day (cacheTimeout = 86400)
      -->
      <param-name>cacheTimeout</param-name>
      <param-value>0</param-value>
    </init-param>

However, it is unlikely developers think about changing this default. Not doing so results in many unneeded requests for resources (resulting in 304). Also note that the resource requests do include an antiCache param already!

Hence, we will change the ResourceServlet to ignore cacheTimeout param and always cache eternally