When the active local endpoint fails, rapidTestOnLocalFallback races the
public endpoint against the remaining local candidates. If a local
candidate wins, RapidTestLocalEndpoints records it as the active local
endpoint but leaves the WireGuard peer alone. The caller is meant to move
the peer, but only did so when no local endpoint was active, which is
never the case once the winner has been recorded.
The peer therefore stayed on the public endpoint while the monitor
treated the site as local: checkLocalEndpoints kept seeing the winner
answer and checkHolepunchEndpoints skipped the site, so nothing moved the
peer or requested relay. A client that can't reach the site's public
endpoint (e.g. one on the site's LAN behind a router without NAT
hairpinning) lost the site until it was restarted.
Move the peer when the winner is still the active local endpoint.
Introduced in 3d88b32 ("Rapid test again when we fail local").
