Investigate flaky test-cli-syntax.js

[Trott]

Failure:

• win2012r2

[Trott]

Stress test to see if flakiness is detectable via stress test: https://ci.nodejs.org/job/node-stress-single-test/90/nodes=win2012r2/

[Trott]

Closing #4064, #4065, and #4066. All three tests were flaky in the same CI build/run on just win2012r2, but have never been flaky before. Stress test runs on all three tests did not produce any test failures. Chalking this up to something weird that probably happened inside CI itself just this one time.

/cc @nodejs/build in case it's something they want to investigate (but totally get it if no one really wants to go down that rabbit hole right now or ever).

[jbergstroem]

If these pop up again we'll have a look.