BUG/MINOR: rhttp: fix reconnect if timeout connect unset

BUG/MINOR: rhttp: fix reconnect if timeout connect unset

Active connect on reverse http relies on connect timeout to detect
connection failure. Thus, if this timeout was unset, connection failure
may not be properly detected.

Fix this by fallback on hardcoded value of 1s for connect if timeout is
unset in the configuration. This is considered as a minor bug, as
haproxy advises against running with timeout unset.

This must be backported up to 2.9.