Core/Database: Correction for later MariaDB version

- Removed unused define CR_INVALID_CONN_HANDLE which was removed entirely in more modern MariaDB versions

src/server/database/Database/MySQLConnection.cpp

@@ -512,7 +512,6 @@ bool MySQLConnection::_HandleMySQLErrno(uint32 errNo, uint8 attempts /*= 5*/)
     {
         case CR_SERVER_GONE_ERROR:
         case CR_SERVER_LOST:
-        case CR_INVALID_CONN_HANDLE:
         case CR_SERVER_LOST_EXTENDED:
         {
             if (m_Mysql)