A bare False from connect() on EADDRINUSE made the gateway reconnect
watcher treat a port conflict as transient and retry forever at the
backoff cap — 1568+ retries over 5 days in a multi-profile production
setup, filling errors.log and leaking 2 ResponseStore fds per retry.
Set a non-retryable fatal error (api_server_port_in_use) in the bind
OSError branch so the platform drops from the reconnect queue;
recover via /platform resume api_server after changing the port.
Re-implementation of #52132 by @msalles1 against the direct-bind path
from #65621 (the pre-probe block their patch targeted no longer
exists). Their production diagnosis and test scenario preserved.