Replaces the ssh-keyscan-based known_hosts population (and the
diagnostic step added to debug its flakiness) with two vars,
GITEA_HOST_KEY and DEPLOY_HOST_KEY, each a full known_hosts-format
line. No extra network calls before the real connections, no TOFU, and
no more risk of tripping aquaria's connection-rate limiting — the
actual root cause of the earlier flakiness was ssh-keyscan opening
multiple near-simultaneous connections (one per probed key type).
haemka
8bb88d0faa
