dev/sg: Disable forced TTY and forced color in NewOutput

[marekweb]

Fix for the error message seen in #41838 #39687 #41507 and #42136 when running sg when stdout is not a terminal (e.g. when piping to another comand).

❗️ An error was returned when detecting the terminal size and capabilities:
   
   GetWinsize: inappropriate ioctl for device

Disabling forceTTY allows terminal detection to work and avoids calling GetWinSize on a non-TTY.

Also disable forceColor based on the same rationale.

Worked on during sg hack hour with @mucles and @danieldides

Test plan

Before

go run ./dev/sg version | less -r

❗️ An error was returned when detecting the terminal size and capabilities:
   
   GetWinsize: inappropriate ioctl for device
   
   Execution will continue, but please report this, along with your operating
   system, terminal, and any other details, to:
     https://github.com/sourcegraph/sourcegraph/issues/new
   
dev

After

go run ./dev/sg version | less -r

dev

[sourcegraph-bot]

Codenotify: Notifying subscribers in OWNERS files for diff 7f29865...e29d4b2.

Notify	File(s)
@mrnugget	dev/sg/internal/std/output.go
@sourcegraph/dev-experience	dev/sg/internal/std/output.go

[mrnugget]

Did you manually confirm that sg lint, sg setup, etc. all still work?

I also wonder whether this wasn't used for the integration tests. If so, an env war should probably be used here to overwrite the behaviour in tests.

[marekweb]

Did you manually confirm that sg lint, sg setup, etc. all still work?

Yes. Also: colors are working in Buildkite logs because, I think, Buildkite stdout emulates a terminal, so it looks like that's still working as intended.

I also wonder whether this wasn't used for the integration tests. If so, an env war should probably be used here to overwrite the behaviour in tests.

I saw that we have SG_DISABLE_OUTPUT_DETECTION which is intended to enable forceTTY and forceColor.

https://github.com/sourcegraph/sourcegraph/blob/9c6b6e2b43865ecc568d7c139dcc9b128ab122c3/dev/sg/main.go#L134-L138

Do you know more about how integration tests might be affected? Would this existing env var cover our needs there?

[mrnugget]

Do you know more about how integration tests might be affected? Would this existing env var cover our needs there?

If the tests pass, then everything should be fine :)