Remove FAKE_CODE from use

This functionality is not used in tests and parts of it didn't work. Since
it is not actively maintained or even used, it is better to remove it.

server/modules/protocol/MySQL/MySQLBackend/mysql_backend.c

@@ -402,9 +402,6 @@ gw_do_connect_to_backend(char *host, int port, int *fd)
     MXS_DEBUG("%lu [gw_do_connect_to_backend] Connected to backend server "
               "%s:%d, fd %d.",
               pthread_self(), host, port, so);
-#if defined(FAKE_CODE)
-    conn_open[so] = true;
-#endif /* FAKE_CODE */
 
 return_rv:
     return rv;