conf: Remove AddDefaultCharset from the default configuration because

      setting a site-wide default does more harm than good.

MFC: 111581
PR: 23421
Reviewed by: fielding, erikabele, jerenkrantz


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.0.x@151264 13f79535-47bb-0310-9956-ffa450edef68