Make sshd_config more flexible regarding connections (#16009)

* Make sshd_config more flexible regarding
MaxStartups and MaxSessions.

See https://man.openbsd.org/sshd_config
for more information.

* make property prefix equals
other existing Gitea SSH properties.

Co-authored-by: dlouzado <dlouzado@senado.leg.br>

docker/root/etc/templates/sshd_config

@@ -5,6 +5,9 @@ AddressFamily any
 ListenAddress 0.0.0.0
 ListenAddress ::
 
+MaxStartups ${SSH_MAX_STARTUPS}
+MaxSessions ${SSH_MAX_SESSIONS}
+
 LogLevel INFO
 
 HostKey /data/ssh/ssh_host_ed25519_key