Fix(lib/win/thread): Ensure `Sleep`'s usage passes over the requested duration under Win7 Fixes rust-lang/rust#149935. See the added comment for more details. This makes the concerned test now reproducibly pass, for us at least. Also, testing this separately revealed successful: see the issue. @rustbot label C-bug I-flaky-test O-windows-7 T-libs A-time A-thread