sshd: disable trigger limit for systemd socket

When startWhenNeeded is enabled, a brute force attack on sshd will cause
systemd to shut down the socket, locking out all SSH access to the machine.
Setting TriggerLimitIntervalSec to 0 disables this behavior.

nixos/modules/services/networking/ssh/sshd.nix

@@ -480,6 +480,8 @@ in
             else
               cfg.ports;
             socketConfig.Accept = true;
+            # Prevent brute-force attacks from shutting down socket
+            socketConfig.TriggerLimitIntervalSec = 0;
           };
 
         services."sshd@" = service;