Add test case for overriding button type

What does this MR do and why?

Add test case for overriding button type

This is a follow-up to !89159 (merged).

Pajamas::ButtonComponent currently allows the type attribute to be overridden via button_options, but it was not covered by a test. This adds that test.

See for example #363946 (closed) where this is relevant, as there's a type="submit" button there.

Screenshots or screen recordings

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How to set up and validate locally

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