macOS ARM64 CI runner often drops testbed log lines

[mhsmith]

Instead, it logs this:

=== Messages dropped during live streaming (use `log show` to see what they were)

For example, see the bottom of "Test App" in https://github.com/beeware/toga/actions/runs/10085243913/job/27885797983.

#2730 added a workaround for the test exit status line, but the fact that other lines are randomly going missing will make it more difficult to deal with other failures, or even know what they are.

[mhsmith]

Originally posted by @freakboy3742 in #2689 (comment)

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Log streaming is currently needed because the test suite is executed inside the app, so we are reliant on the app's output to evaluate test success. One of the approaches to #2662 is to modify the testbed so that the test suite runs locally, and communicates with the app via a remote control mechanism. This would mean we don't need to use the system log - we could use vanilla stdout handling for test reports.

[mhsmith]

Originally posted by @mhsmith in #2689 (comment)

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What if std-nslog had an option to output to BOTH the system log and the original stdout? Then we could start GUI and console apps in the same way, by calling their executable directly instead of using open, and not use the system log at all.

[mhsmith]

Originally posted by @freakboy3742 in #2689 (comment)

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I guess that could be an option; although an option to std-nslog isn't required in this case - if "run in test mode" means direct binary execution, we can just not install the std-nslog handler when running in test mode. The only reason std-nslog is needed at all is to surface the logs from inside an app started with open; if we're not using open, we don't need to process the logs.

My one hesitation is whether directly starting the executable will modify the properties of the app at runtime. I know there's definitely a change in how command line arguments are handled; but there might also be some changes around how permissions and other runtime app properties are handled.