Make sure the filter stack in a reused downstream connection is reset

so we don't get lots of DECHUNK filters when we don't want them.
PR:
Obtained from:
Reviewed by:


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@88797 13f79535-47bb-0310-9956-ffa450edef68