Lightstep tracing stalls with 10k repos

Created by: ijt

Tracing would help us debug performance issues, but it's not working consistently.

To see the problem:

1. Open Firefox (Chrome's network tab wasn't working for this on my system)
2. Go to sourcegraph.com, right click, and click Inspect Element.
3. Click the network tab in the dev panel that comes up.
4. Search for something such as foo.
5. Click the top network item that comes up.
6. Click the link to the right of the x-trace header to see the trace on lightstep.com.

A trace should appear but instead it just spins.