BUG/MINOR: http-ana: Adjust the server status before the L7 retries

BUG/MINOR: http-ana: Adjust the server status before the L7 retries

The server status must be adjusted, if necessary, at each retry. It is
properly performed when "obersve layer4" directive is set. But for the layer
7, only the last attempt was considered.

When the L7 retries were implemented, all retries were added before the
server status adjutement. So only the last attempt was considered. To fix
the issue, we must adjut the server status first, and then try to perform a
L7 retry.

This patch should fix the issue #2679. It must be backported to all stable
versions.

(cherry picked from commit 2a5da31ccef239e21d17ec34430fdc6b51b9cc67)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>