git-codereview: wait longer for Gerrit

5 seconds turns out to be far too optimistic.
I am seeing 15 seconds regularly today.

Change-Id: Ia258d340f04e294a2bf40d0119170e8083b9fb6b
Reviewed-on: https://go-review.googlesource.com/11192
Reviewed-by: Andrew Gerrand <adg@golang.org>
1 file changed