Move formula Bundler defaults to superenv

[cho-m]

Put all common defaults in our superenv (similar to Python, Cargo, etc. environment variables). This avoids having to add these to every Bundler-installed formula we distribute. And sets our preferred defaults for any nested calls to Bundler.

Switching to :-separated BUNDLE_WITHOUT for better compatibility with older Bundler (in case any formulae are using old system Bundler).

BUNDLE_PATH remains as it differs in fetch vs. install. In Bundler 5, we will likely need to move BUNDLE_PATH from fetch to install phase due to changes.

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[Copilot]

🟡 Changes recommended

The newly centralised Bundler behaviour needs direct Superenv regression coverage.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Moves shared Bundler defaults into Superenv so formula builds and nested Bundler calls inherit consistent settings.

Changes:

• Configures Bundler’s platform, version and excluded groups through Superenv.
• Removes redundant configuration commands from generated Ruby formulae.

File summaries

File	Description
Library/Homebrew/formula_creator.rb	Removes per-formula Bundler defaults.
Library/Homebrew/extend/ENV/super.rb	Adds shared Bundler environment defaults.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Balanced

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[MikeMcQuaid]

Thanks!