[openmp] Add option to disable tsan tests (#111548)

This adds a OPENMP_TEST_ENABLE_TSAN option that allows to override
whether tests using tsan will be enabled. The option defaults to the
existing auto-detection.

The background here is
https://github.com/llvm/llvm-project/issues/111492, where we have some
systems where tsan doesn't work, but we do still want to build it and
run tests that don't use tsan.

GitOrigin-RevId: b2edeb58b8cb3268acee425cd52b406eb60a8095
3 files changed