BUG/MEDIUM: http-ana: Don't ignore L7 retry errors

BUG/MEDIUM: http-ana: Don't ignore L7 retry errors

with L7 retries are configured, when the max number of retries is reached
the error must be reported to the client. However, when it was an abort on a
reused connections, the client connection is silently closed. While it is
expected without L7 retries, to let the client retries on its own, it is
unexepcted with L7 retries.

So let's fix it by ignoring the SF_SRV_REUSED flag on the stream when a L7
retry fails. This way, a 502/425 will be reported to the client.

This patch should help to fix the issue #3414. It must be backported to all
supported versions.