gh-110850: Use _PyDeadline_Get() in EnterNonRecursiveMutex() (#118556)

Use _PyDeadline_Init() and _PyDeadline_Get() in
EnterNonRecursiveMutex() of thread_nt.h.

_PyDeadline_Get() uses the monotonic clock which is now the same as
the perf counter clock on all platforms. So this change does not
cause any behavior change. It just reuses existing helper functions.