If the user's running "go test" by hand, no need to spam stderr with
the sentinel marker. It already calls t.Logf (which only gets output
on actual failure, or verbose mode) which is enough to tell users it's
known flaky. Stderr OTOH always prints out and is distracting to
manual "go test" users.
Updates #cleanup
Change-Id: Ie5e6881bae291787c30f75924fa132f4a28abbb2
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
0396366aae