refactor(oxlint): use vitest expect rather than node:assert in test cases

[camc314]

Using vitest's expect here is more idomatic, considering we're using vitest for our tests, and it should give us better diffs in case of failures.

[camc314]

• refactor(oxlint): use vitest expect rather than node:assert in test cases #15988 👈 (View in Graphite)
• main

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[Copilot]

Pull request overview

This PR refactors the test file to use Vitest's native expect API instead of Node's assert module, aligning with the existing testing patterns used throughout the codebase and improving test failure diagnostics.

• Removes dependency on node:assert module in favor of Vitest's built-in assertions
• Converts all assert.deepStrictEqual calls to expect().toEqual() for consistency with other test files
• Maintains identical test logic while improving readability and error reporting

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[overlookmotel]

Superceded by #16016.