Revert hydration optimisation

[Conduitry]

This reverts the buggy hydration optimisation from #6204 for the time being.

Are there some tests from other PRs that we might as well pull in now, or should that be separate?

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• Ideally, include a test that fails without this PR but passes with it.

Tests

• Run the tests with npm test and lint the project with npm run lint

[benmccann]

Lgtm. The test from #6283 might be worth including. But you could merge this, revert the code changes from that PR, and then merge that one if it's easier than trying to pull them in here

[Conduitry]

👍 Yup, I've now cherry picked the two commits from that PR that added tests.