Disable stacktrace
Disable stacktrace

Summary:
```

17:05

2018-08-27T23:27:50.124Z        ERROR   scheduler/events.go:318 Error announcing: announcing disabled   {"hash": "b29a10651f33420a1506a2d8619df40b1a4ce653"}
code.uber.internal/infra/kraken/lib/torrent/scheduler.announceErrEvent.Apply
        /home/udocker/kraken-origin/.tmp/.goroot/src/code.uber.internal/infra/kraken/lib/torrent/scheduler/events.go:318
code.uber.internal/infra/kraken/lib/torrent/scheduler.(*defaultEventLoop).Run
        /home/udocker/kraken-origin/.tmp/.goroot/src/code.uber.internal/infra/kraken/lib/torrent/scheduler/events.go:76
code.uber.internal/infra/kraken/lib/torrent/scheduler.(*scheduler).runEventLoop
        /home/udocker/kraken-origin/.tmp/.goroot/src/code.uber.internal/infra/kraken/lib/torrent/scheduler/scheduler.go:345
```

Reviewers: #kraken, codyg

Reviewed By: #kraken, codyg

Subscribers: jenkins

Differential Revision: https://code.uberinternal.com/D2020817

uber/kraken,uber/kraken,uber/kraken,uber/kraken,uber/kraken