Misc: Use [[fallthrough]] attribute instead of comment to mark intentional fallthroughs

src/server/database/Database/MySQLConnection.cpp

@@ -521,8 +521,8 @@ bool MySQLConnection::_HandleMySQLErrno(uint32 errNo, uint8 attempts /*= 5*/)
                 mysql_close(m_Mysql);
                 m_Mysql = nullptr;
             }
+            [[fallthrough]];
         }
-        /* fallthrough */
         case CR_CONN_HOST_ERROR:
         {
             TC_LOG_INFO("sql.sql", "Attempting to reconnect to the MySQL server...");