test: refactor hmr-ssr tests

[sapphi-red]

Description

This PR contains the following changes:

• remove util functions declared in hmr-ssr.spec.ts and use the same functions declared in test-utils.ts
  • also run the tests in playground-temp
• only run hmr-ssr test on test-serve (dont run it on test-build) because the tests only makes sense for serve
• removed todo from tests and fixed to make them passing
• removed todo tests that are not relevant for SSR

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[bluwy]

Nice!