HPCC-12754 Remove an extra variable in WsTopology.TpLogFile

The WsTopology.TpLogFile returns a chuck of a log file
(LogData) in the TpLogFileResponse. An old http_content
variable (thefile) defined inside the TpLogFileResponse
causes the response not work for a json request. Since the
thefile is not used any more, this fix removes the old
variable.

Signed-off-by: wangkx <kevin.wang@lexisnexis.com>