Tests: un-skip a few libc++ tests that were believed to have timing assumptions

[cpplearner]

• std/atomics/atomics.types.operations/atomics.types.operations.wait/atomic_notify_all.pass.cpp
  • The timing assumption has been removed by https://github.com/llvm/llvm-project/commit/b3b611fe1a2f41e3e3ccf294c3fd9b1316e70c4d and https://github.com/llvm/llvm-project/commit/e98195f318375978e3e0b153cade8bb3a05029bb.
• std/thread/thread.mutex/thread.lock/thread.lock.guard/adopt_lock.pass.cpp
  • The timing assumption has been removed by https://github.com/llvm/llvm-project/commit/a675c1dee483129611794f37e0867f565181827b.
• std/thread/thread.mutex/thread.lock/thread.lock.guard/mutex.pass.cpp
  • The timing assumption has been removed by https://github.com/llvm/llvm-project/commit/a675c1dee483129611794f37e0867f565181827b.
• std/thread/thread.threads/thread.thread.class/thread.thread.destr/dtor.pass.cpp
  • It doesn't seem to have timing assumptions. (There's a sleep_for call, which seems redundant.)
• std/thread/thread.threads/thread.thread.class/thread.thread.member/detach.pass.cpp
  • It doesn't seem to have timing assumptions.

Drive-by: move two XFAIL: msvc tests down to "XFAILs WHICH PASS" section.

[StephanTLavavej]

I'm nervous about anything that says "detach", but if it flakes out we can re-skip it. Thanks!

[StephanTLavavej]

I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.

[StephanTLavavej]

Thanks for improving our libc++ test coverage! :white_check_mark: :tada: :smile_cat: