install: set swappiness to 1 by default

install/install.ts

@@ -405,6 +405,8 @@ connect-timeout = 10`);
                 'hydrooj install https://hydro.ac/language-server-0.0.1.tgz',
                 'pm2 restart hydrooj',
             ],
+            'echo "vm.swappiness = 1" >>/etc/sysctl.conf',
+            'sysctl -p',
             ['pm2 install pm2-logrotate', { retry: true }],
             'pm2 set pm2-logrotate:max_size 64M',
         ],