content/http-tracing: remove Dave Cheney

He mentioned that the project is a group effort, hence we should
not single out his name.

Change-Id: I775a37fa8d7a231942642809c85652e58d0edb08
Reviewed-on: https://go-review.googlesource.com/30352
Reviewed-by: Andrew Gerrand <adg@golang.org>
1 file changed