HPCC-12754 Remove an extra variable in WsTopology.TpLogFile

The WsTopology.TpLogFile returns a chuck of a log file in
the LogData variable. An old http_content variable (thefile)
inside the TpLogFileResponse is no longer used and causes
the response not work for a json request. This fix removes
the old variable.

Signed-off-by: wangkx <kevin.wang@lexisnexis.com>