Increase the sleep and wait for up to 2 seconds for the dup2.
Apparently it can sometimes take a long time.

Fixes #23784

Change-Id: I929530b057bbcd842b28a7640c39dd68d719ff7d
Reviewed-on: https://go-review.googlesource.com/93895
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>