Remove Python 2 use of std{out,err} over std{out,err}.buffer

[Eric-Arellano]

No description provided.

[stuhood]

This one feels likely to cause cherry-pick conflicts to 1.17.x. Let's hold off a few more days, since @blorente might need one more round to stabilize pantsd there before it is finalized.

[Eric-Arellano]

This one feels likely to cause cherry-pick conflicts to 1.17.x.

I don't think it's very likely to cause an actual merge conflict, since the logic around stdout.buffer has been stable for the past few months. The only merge conflict I could imagine is if we were to change any of this code around stdout.buffer, which I don't anticipate happening.

Fine waiting need be, but don't think it's necessary here.

[blorente]

After reading through the changes, there are a couple of files that are likely to change in the next round of pantsd fixes, (exception_sink.py, exiter.py, pants_daemon.py and remote_pants_runner.py).

However, I find it hard to imagine modifying these specific lines in the pantsd fixes, so I don't think we should halt the progress of upstream for that.

[Eric-Arellano]

Only failure is flake from #7856.