doveadm-server: Deinitialize print on connection destroy

Otherwise print remains initialized and can break when reusing the service.

src/doveadm/client-connection.c

@@ -561,6 +561,8 @@ void client_connection_destroy(struct client_connection **_conn)
 
 	*_conn = NULL;
 
+	doveadm_print_deinit();
+
 	if (conn->ssl_iostream != NULL)
 		ssl_iostream_destroy(&conn->ssl_iostream);