test(query-core): use fake timers for queryObserver.test.tsx (#9004)

* test(query-core): use fake timers for queryObserver.test.tsx

* chore: update

* chore: migrate

* chore: update

* Removes unused testing library dependency

Deletes `@testing-library/dom` from devDependencies in package.json and pnpm-lock.yaml to clean up unused dependencies and streamline the project's dependency tree.

* chore: update

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Co-authored-by: Dominik Dorfmeister <office@dorfmeister.cc>