Remove leftover code for --no-quarantine

[cho-m]

Drop code that was used for no longer available --no-quarantine.

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[Copilot]

Pull request overview

This PR removes now-obsolete support code for the former --no-quarantine behavior across Cask download/install/upgrade paths, simplifying APIs and making quarantine handling unconditional where applicable.

Changes:

• Remove quarantine keyword parameters and related branching from Cask installer/download/upgrade flows.
• Update commands/dev-cmds to stop passing quarantine: options that are no longer meaningful.
• Adjust specs and API helpers to match the simplified interfaces.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Library/Homebrew/test/cask/upgrade_spec.rb	Updates expectations around Cask::Installer.new invocation after removing quarantine options.
Library/Homebrew/test/cask/download_spec.rb	Stops passing quarantine: true to Cask::Download in tests.
Library/Homebrew/env_config.rb	Removes cask_opts_quarantine? option parsing logic.
Library/Homebrew/dev-cmd/unpack.rb	Removes explicit quarantine: true when creating Cask::Download.
Library/Homebrew/dev-cmd/bump-cask-pr.rb	Removes explicit quarantine: true when fetching a Cask::Download.
Library/Homebrew/dev-cmd/audit.rb	Stops passing quarantine through to cask auditing.
Library/Homebrew/cmd/reinstall.rb	Removes quarantine: true from reinstall invocation.
Library/Homebrew/cmd/fetch.rb	Removes quarantine: true from cask/API download enqueueing.
Library/Homebrew/cask/upgrade.rb	Removes quarantine plumbing from upgrade entrypoints and installer construction.
Library/Homebrew/cask/reinstall.rb	Removes quarantine plumbing from cask reinstall flow.
Library/Homebrew/cask/installer.rb	Removes quarantine state/warnings and stops forwarding quarantine to downloaders/dependency installers.
Library/Homebrew/cask/download.rb	Removes quarantine toggle support; quarantine application is now unconditional (when available).
Library/Homebrew/cask/auditor.rb	Removes quarantine plumbing from the auditor API.
Library/Homebrew/cask/audit.rb	Removes quarantine option when instantiating downloads for audits.
Library/Homebrew/api/cask_download.rb	Removes quarantine parameter from the API download helper and its Cask::Download construction.

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[carlocab]

This probably needs a deprecation cycle too, since, before this, HOMEBREW_CASK_OPTS=--no-quarantine I think still skipped quarantine (even if we deprecated/disabled brew install --cask --no-quarantine).

[MikeMcQuaid]

Thanks!

As per @carlocab's comment: I don't think we need another deprecation pass here. We deprecated this in https://brew.sh/2025/11/12/homebrew-5.0.0/ not far off a year ago and this is undocumented behaviour that happens to have kept working here.

[p-linnane]

I agree that this doesn't need a deprecation cycle.