Revert "testing: add Output"

Revert "testing: add Output"

This reverts commit 8d189f188e225e4919b34c0c097e75dfda255949.

Reason for revert: failing test

Change-Id: I951087eaef7818697acf87e3206003bcc8a81ee2
Reviewed-on: https://go-review.googlesource.com/c/go/+/672335
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>