* Reduce task logger noise: stop duplicating every log entry to glog and stderr
Every task log entry was being tripled: written to the task log file,
forwarded to glog (which writes to /tmp by default with no rotation),
and echoed to stderr. This caused glog files to fill /tmp on long-running
workers.
- Remove INFO/DEBUG forwarding to glog (only ERROR/WARNING remain)
- Remove stderr echo of every log line
- Remove fsync on every single log write (unnecessary for log files)
* Fix glog call depth for correct source file attribution
The call stack is: caller → Error() → log() → writeLogEntry() →
glog.ErrorDepth(), so depth=4 is needed for glog to report the
original caller's file and line number.
2ff4a07544