--grouped truncates long build output

[ecraig12345]

With the --grouped option and a task with very long output, some of the output is getting truncated (at least on errors). This is a problem because it can make determining the source of an error impossible--2 examples in this build. I've disabled grouped builds in Fluent UI for now (microsoft/fluentui#16019) so that we can actually debug these issues, but I'd like to re-enable the option since it's a better experience in general.

[kenotron]

The problem also with --grouped is that it buffers... so if things are timed out, the log would actually never be written. I think if the log is supposed to be long, maybe turning it off is good enough? What do you think?

[ecraig12345]

Yeah turning it off is how we've worked around the issue so far. Some other ideas:

• Can we make lage detect when it's about to be killed and flush the logs?
• Maybe add a way to turn off grouping per project? (though for occasional weird issues or PRs that introduce new hangs, that wouldn't help)