Don't buffer stdout.

Emulate a tty to prevent stdout from being implicitly buffered for all
top-level workflows.
This prevents stdout/stderr from being printed in the wrong order for
these cases:
1. Running a workflow non-interactively, such as in infra.
2. Running a test workflow target via `bazel run` or `bazel test`.

Also remove duplicate publish task in test package workflow.

Fixed: 119214
Change-Id: Icf73d0cf2e075b518c95f180fc7f5517d1b975de
Reviewed-on: https://fuchsia-review.googlesource.com/c/sdk-integration/+/791182
Reviewed-by: Jiaming Li <lijiaming@google.com>
Commit-Queue: Darren Chan <chandarren@google.com>