When a sticky fallback IP (from DoH discovery) becomes unreachable,
the transport previously got stuck in an attempt_order that only
tried the dead IP. This prevented the gateway from recovering
until the service was restarted.
Changes:
- Always include primary DNS path (None) after the sticky IP in the
attempt_order so that a primary-path retry happens on sticky failure.
- Reset self._sticky_ip to None when the currently sticky IP hits
a connect timeout / connect error, allowing the next request to
retry from scratch.
Fixes silent Telegram disconnection when discovered fallback IPs
are transiently or permanently unreachable.
5c4b43ced7