This is an attempt at deflaking the e2e exec tests, and a way to improve
messages.
e2e occasionally fail with "unexpected EOF" even though the exec output matches
expectations. I suspect there is a race in handling EOF in server/http handling.
Here, we special case this error and ensures we get all failures,
to help debug the case better.
* Adds a constraint to prevent tests from landing on Windows
* Improve Terraform output for mixed windows/linux clients
* Makes some Windows client config fixes from 0.10.2 testing
