extend/kernel: fix duplicate messages in GitHub Actions

[carlocab]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew typecheck with your changes locally?
• Have you successfully run brew tests with your changes locally?

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Calls to opoo and onoe produce duplicate Warning: and Error:
messages in CI logs because we print something to stdout and print an
annotation. Annotations also produce Error: and Warning: lines in
the log.

Let's fix this by skipping printing the message if we've already printed
an annotation.

[MikeMcQuaid]

Do you have an example of this in the wild?

[carlocab]

Yes. Every error in Homebrew/core:

• https://github.com/Homebrew/homebrew-core/actions/runs/11320784561/job/31478920324?pr=174126#step:3:390
• https://github.com/Homebrew/homebrew-core/actions/runs/11321464776/job/31480638674#step:3:560
• https://github.com/Homebrew/homebrew-core/actions/runs/11320653039/job/31478580022?pr=194310#step:4:83
• https://github.com/Homebrew/homebrew-core/actions/runs/11318361810/job/31473523401?pr=194269#step:3:1828
• https://github.com/Homebrew/homebrew-core/actions/runs/11318570674/job/31473367240?pr=193315#step:3:334
• https://github.com/Homebrew/homebrew-core/actions/runs/11296126169/job/31420419193?pr=193787#step:4:98
• etc

[MikeMcQuaid]

Thanks, makes sense!