Revert "MEDIUM: http-ana: Deal with L7 retries in HTTP analysers"

Revert "MEDIUM: http-ana: Deal with L7 retries in HTTP analysers"

This reverts commit 5b82cc5b5c350c7cfa194cc6bc16ad9308784541. The purpose of
this commit was to fully handle L7 retries in HTTP analysers and stop to
deal with the L7 buffer in si_cs_send()/si_cs_recv(). It is of course
cleaner this way. But there is a huge drawback. The L7 buffer is reserved
from the time the request analysis is finished until the moment the response
is received. For a small request, the analysis is finished before the
connection to the server. Thus for the L7 buffer will be kept for queued
sessions while it is not mandatory.

So, for now, the commit is reverted to go back to the less expensive
solution. This patch must be backported to 2.4.