[CMake] Disable LLVM_INCLUDE_GO_TESTS by default

llvm/test/Bindings/Go is quite flaky in the past few months and nobody fixes it.

See

* https://lists.llvm.org/pipermail/llvm-dev/2021-December/154353.html "Suggestions on debugging pre-merge test failure that looks irrelevant."
* https://github.com/llvm/llvm-project/issues/53017

Reviewed By: aeubanks

Differential Revision: https://reviews.llvm.org/D116698