hotfix: add react-ga4

[dupreesi]

Issues this PR relates to

adds GA4 to prod

NOTE: REMEMBER NOT TO REVIEW UNLESS ALL ACCEPTANCE CRITERIA HAS BEEN TICKED OFF

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Any info the reviewer needs to know to test

e.g. Add env vars, run npm install

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Any info the team needs to consider before merged into development

e.g. Will a database need to be rebuilt (and is this ok if existing data), add env vars

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