Use keyword-only parameters in tests

[adamtheturtle]

Summary

• Enforce keyword-only arguments (using *) in test functions that accept multiple parameters
• This improves call-site clarity and prevents accidental positional argument errors

Test plan

• Verify tests still pass

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Note

Low Risk
Mechanical test-signature change only; risk is limited to potential pytest collection/parametrization edge cases if any test relies on positional arguments.

Overview
This PR changes many pytest test functions (and one CI linter test) to enforce keyword-only parameters by adding * to function signatures.

No runtime behavior is intentionally changed; the update is a broad signature/style adjustment across the mock VWS test suite to make argument passing explicit and reduce accidental positional ordering mistakes.

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