test(svelte-query-persist-client/PersistQueryClientProvider): switch to fake timers, replace 'waitFor' with 'advanceTimersByTimeAsync', and use 'sleep().then()' pattern

test(svelte-query-persist-client/PersistQueryClientProvider): switch to fake timers, replace 'waitFor' with 'advanceTimersByTimeAsync', and use 'sleep().then()' pattern #6877