ProxySQL ping monitor error

[hlb15294934267]

• A clear description of the issue：After the ping monitor module detects that a MySQL node goes offline, the status of the node is set to SHUNNED. After the node is restarted, the status of the node remains SHUNNED and is not changed to ONLINE.
• ProxySQL version：2.6
• OS version：CentOS Linux release 7.9.2009 (Core)
• The steps to reproduce the issue：
  1）start ProxySQL and config mysql_servers;
  2）kill MySQL node(eg：3307);
  3）check MySQL node status(SHUNNED);
  4）restart MySQL node;
  5）check MySQL node status，the node remains SHUNNED and is not changed to ONLINE.