TS-2162: Auto-created collation LogObject would be misused by access log

When collation host receives LogBuffer data from network, it'll create
LogObject according the data's format automatically.

Since the LogFilter of these auto-created LogObjects are empty, they
will be misused by access log generated by collation host itself –
toss_this_entry() will always return false when m_does_conjunction is
set.

This patch introduces a new member variable: m_auto_created in LogObject,
so that we can distinguish this type of LogObject to avoid misusing.