Remove unused rounding modes Trunc and Expand

[barakman]

Fixes #5411

In the Rounding-Modes API (in the Math library):

    enum Rounding {
        Floor, // Toward negative infinity
        Ceil, // Toward positive infinity
        Trunc, // Toward zero
        Expand // Away from zero
    }

Remove the last two options, which are not in use throughout the codebase.

PR Checklist

• Tests
• Documentation
• Changeset entry (run npx changeset add)

[changeset-bot]

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Latest commit: c0eae73

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[barakman]

⚠️ No Changeset found

Latest commit: 6a441be

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets
Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

This PR introduces an API-breaking change, so in theory, the changeset should include a major-version update.
On the other hand, the changed part in the API is not used anywhere in the current version, so it is possible that a minor-version update or even a patch-version update will suffice.