Reverse r168030 because the not-acceptable (406)

custom error doc can't provide all the information
provided by the internal doc.  Also delete the corresponding
.html.var file to avoid future confusion.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@178453 13f79535-47bb-0310-9956-ffa450edef68