test(query-test-utils): init (internal package) (#9095)

* test(query-test-utils): init

* refactor(tests): replace createQueryClient with new QueryClient instantiation across test files

* refactor(tests): remove unused imports in utils test file

* refactor(tests): replace fetcher functions with sleep-based implementations in query tests

* refactor(tests): replace simpleFetcher with sleep-based implementations in query tests

* fix(query-core): update test:build script to remove pnpm prefix

* refactor(tests): extract query function into a variable for clarity in useQuery tests

* chore(tsconfig): remove temporary Vitest TypeScript configuration file

* chore: add @tanstack/query-test-utils as a devDependency in multiple packages

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