[asan] Hide SetTLSFakeStack and replaces uses with ResetTLSFakeStack (#163674)
To simplify implementation of
https://github.com/llvm/llvm-project/pull/160135
To keep the logic of figuring out what should be in TLS to one place.
The rest of the code should just reset it and rely on
GetFakeStackFast()/GetFakeStackFastAlways().