Before this change, combining `check_call` with `tee` had the undesirable effect that even when a step fails, check_call still succeeded (because of `tee`).
Before this change, combining `check_call` with `tee` had the undesirable effect that even when a step fails, check_call still succeeded (because of `tee`).

So, I'm switching to using Popen to make sure we can fail earlier properly when any of the steps failed.

PiperOrigin-RevId: 375492420

google/deepvariant,google/deepvariant,google/deepvariant