The timeouts were increased in CL 2462 and CL 2510
to work around a slowness issue when running Go
programs on a Plan 9 machine on GCE.

Since we figured out this issue, we can restore
the timeouts to their original values.

Updates #10028.

Change-Id: I2e5b91666461715df69df97ea791f3d88d9de4d0
Reviewed-on: https://go-review.googlesource.com/6261Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>