The intermittent failure have likely been fixed by a recent round of general fixes in the new x64 backend. This basically reverts https://github.com/bytecodealliance/wasmtime/pull/2100 and uses the CI script there.
run-experimental-x64-ci
This makes it possible to run a subset of the tests with e.g. `./ci/run-experimental-x64-ci.sh -- wast::Cranelift::spec`.
Co-authored-by: Andrew Brown <andrew.brown@intel.com>