Replace CLockFreeGuard with AtomicMutex

[prasannavl]

/kind fix

• CLockFreeGuard uses barrier that's unsuitable for general use case, and results in multiple threads entering critical sections due to premature barrier optimizations
• Additionally, remove the 1ms thread sleep, which on platforms like Linux which default to higher resolution thread quantums might be palatable, but will have heavy regressive behaviour on platforms like Windows which default to 15ms quantum slices.
• Since CLockFree is primarily used for extremely cheap ops, spin waiting is just simpler // though likely have to reassess it's use cases later on if it's even useful here.

[prasannavl]

Closed in favor of #1797