Revert merge of contract testing

What does this MR do and why?

The Pact dependency does some calls to google analytics during install.

This is concerning, as it is not opt-in and sending GitLab developer data to GA / a third party without consent. Same for people installing from source.

Furthermore it seems like an independent thing from our "normal" frontend stack, so we should consider if this could live in a separate package.json (like e.g. storybook) in order to reduce friction when updating e.g. jest or other dependencies.

Screenshots or screen recordings

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How to set up and validate locally

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MR acceptance checklist

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