Enable privileged tap CI containers

[MikeMcQuaid]

• Allow Bubblewrap user namespaces in generated GitHub Actions container jobs.
• Direct GitHub Actions sandbox failures to the matching container configuration.

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OpenAI Codex 5.6 Terra high with local review and testing.

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[Copilot]

Pull request overview

This PR updates Homebrew’s Linux diagnostics and the brew tap-new GitHub Actions workflow template to better handle Bubblewrap sandbox failures in GitHub Actions, particularly when container execution needs additional privileges.

Changes:

• Add Linux diagnostic output suggesting --privileged for GitHub Actions environments when the sandbox is unavailable.
• Update brew tap-new’s generated tests.yml workflow to add container privilege options.
• Add/extend specs to validate the new diagnostic and workflow generation behavior.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
Library/Homebrew/extend/os/linux/diagnostic.rb	Adds GitHub Actions-focused guidance when the Linux sandbox is unavailable.
Library/Homebrew/dev-cmd/tap-new.rb	Updates the generated tests.yml workflow template to include privileged container options.
Library/Homebrew/test/os/linux/diagnostic_spec.rb	Adds a spec covering the new diagnostic suggestion text.
Library/Homebrew/test/dev-cmd/tap-new_spec.rb	Updates the integration spec to assert the new workflow content.

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